JP2003152289A - Printed wiring board and multi-layer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reinforce a key plate portion by a simple method to prevent the warpage of a printed wiring board and a multi-layer printed wiring board during reflow. SOLUTION: In this printed wiring board, a metallic reinforcing plate is buried at the center inside a key plate portion 2 that is formed in the outer periphery of a printed board body 1. In addition, another metallic reinforcing plate is buried in the key plate portion in at least one layer of a printed wiring board of laminated printed wiring board in the multi-layer printed wiring board 1. The key plate portion is provided with perforation for discarding or a V groove.

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 and a multilayer printed wiring board, and more particularly to a printed wiring board and a multilayer printed wiring board which prevent warpage during reflow to reduce defective soldering.

[0002]

2. Description of the Related Art When a component is placed on a printed wiring board and soldering is performed by reflow, the printed wiring board may be warped or bent due to heat received during the reflow. This warpage is one of the causes of the solder bridge and component shift.

In recent years, in particular, in order to miniaturize electronic equipment, a multilayer printed wiring board manufactured by a build-up method (hereinafter referred to as a build-up board) has been used. In general, since the board thickness is thinner than that of the printed wiring board, the board strength is weak and warpage is likely to occur during reflow.

Conventionally, the following methods (1), (2), (3) and (4) are known as methods for preventing warpage during reflow.

(1) Method using a jig dedicated to warp prevention:
For example, Japanese Unexamined Patent Publication No. 06-244242 discloses a technique in which a jig having high strength and heavy weight is placed on a printed wiring board during reflow to prevent warping due to the weight of the jig.

(2) Method of forming a pattern on a discarded substrate (No. 1): In Japanese Patent Laid-Open No. 10-322035, strip-shaped conductor patterns are arranged at equal intervals on a discarded substrate of each layer of a multilayer printed wiring board, and There is disclosed a technique for preventing warpage by forming the patterns by shifting the pattern direction by 90 degrees for each layer. The discarded board is a blank portion added to the board body used as a product for handling and positioning of the printed wiring board, and is usually separated from the board body and discarded after soldering the components.

(3) Method for forming a pattern on the discard plate (part 2): Japanese Patent Laid-Open No. 11-177191 discloses
A method as shown in FIG. 7 is disclosed. That is, in a printed wiring board having a main body portion 71 on which a wiring pattern is formed and a discarding board portion 72 provided on the outer peripheral edge portion of the main body portion 71 and on which no wiring pattern is formed, the conveyance direction during component mounting A solid pattern 74 is formed on the discarding plate portion 72a on the vertical side, and a plurality of divided dummy patterns 73 are formed on the discarding plate portion 72b on the side parallel to the transport direction during component mounting. The solid pattern 74 has higher rigidity against heat during reflow, and the dummy pattern 73 reduces the difference in the amount of heat shrinkage between the substrate and the pattern to reduce warpage.

(4) Method of increasing the number of stacked waste substrates:
Japanese Patent Laid-Open No. 2001-7453 discloses a method as shown in FIG. That is, the number of layers of the discarded substrates 63 is made larger than that of the substrate body 62 to form the reinforced laminated portion 68.
The discarding substrate 63 is thicker than the substrate main body 62 by the amount corresponding to the reinforcing laminated portion 68, the substrate strength is improved, and warpage during reflow is prevented.

[0009]

[Problems to be Solved by the Invention] However, (1)
In the method of using the jig for preventing warpage, it is necessary to prepare various kinds of jigs having different shapes and dimensions, and to use the jig properly according to the type of the printed wiring board. There is a problem that it is troublesome because it is necessary to attach and remove the tool.

In the methods (2) and (3) of forming a pattern on the discarded substrate, the strength of the pattern itself is weak, so that the effect of preventing warpage is insufficient, and the dummy pattern for reducing the difference in heat shrinkage is used. There is a problem that it is not effective unless the area is wide.

Further, in the method (4) of increasing the number of stacked discarded substrates, there is almost no difference in the strength when one or two layers are stacked on the discarded substrate portion and the thickness is made thicker than the main body portion. Since it is thicker than the main body, the difference in height becomes a bottleneck during solder printing, and not only the conventional solder printing equipment cannot be used as it is, but also the productivity decreases because the number of manufacturing processes for printed wiring boards increases. .

[0012]

A printed wiring board according to the present invention is a quadrilateral main body portion on which a wiring pattern, which is a product portion, is formed, and a non-product waste disposed on an outer peripheral edge portion of the main body portion. In a printed wiring board having a board portion,
The discard plate portion is formed by embedding a metal reinforcing plate inside.

Further, the abandonment plate portion may be provided only on two sides perpendicular to the conveying direction when the parts are mounted on the main body portion and reflowed.

The reinforcing plate may have a shape in which the outer edge side is bent.

The multilayer printed wiring board of the present invention has a quadrilateral main body portion having a wiring pattern, which is a product portion, and a waste plate portion, which is provided outside the product and is provided on the outer peripheral edge of the main body portion. In a multilayer printed wiring board in which a plurality of printed wiring boards are laminated, at least one of the printed wiring boards is formed by embedding a metal reinforcing plate in the discarding plate portion.

Further, the discarding plate portion may be provided only on two sides perpendicular to the conveying direction when the parts are mounted on the main body portion and reflowed.

Further, in the printed wiring board and the multilayer printed wiring board of the present invention, the boundary between the main body portion and the discarding board portion may be provided with a perforation for splitting.

Alternatively, a V-groove for splitting may be provided at the boundary between the main body portion and the discarding plate portion.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 1 is a front view showing an embodiment of the printed wiring board of the present invention, FIG. 2 is a sectional view showing an embodiment of the printed wiring board in FIG. 1, and FIG. 3 is another drawing of the printed wiring board of the present invention. Sectional view showing an embodiment example,
FIG. 4 is a sectional view showing an embodiment of a multilayer printed wiring board according to the present invention, and FIG. 5 is a sectional view showing another embodiment of a multilayer printed wiring board according to the present invention.

Referring to FIG. 1, a printed wiring board of the present invention is a quadrilateral body portion 1 on which a wiring pattern, which is a product portion, is formed, and a waste plate which is provided outside the product and is provided on the outer peripheral edge of the body portion 1. A metal plate using an aluminum plate, a copper plate, a zinc plate, or the like.
It is formed by embedding a reinforcing plate. The boundary between the main body portion 1 and the discarding plate portion 2 is provided with perforations 3 for splitting. A slit 8 is provided between the perforations so that the perforations can be easily split.

Further, instead of providing the perforations 3 and the slits 8, V-grooves may be provided at the boundary, which has an advantage that the split surface is rough but the processing is easy.

The discard plate portion 2 is a portion added to the main body portion for handling, positioning, etc. in the manufacturing process of the printed wiring board or the multilayer printed wiring board, and is a portion to be discarded in the final step.

Further, FIG. 1 shows an example in which the waste plate portions 2 are provided on the four sides of the main body portion 1, but when the warpage during reflow is relatively weak, the parts are mounted on the printed wiring board. The discarding plate portion 2 may be provided only on the two sides on the right and left sides only if the secondary direction is perpendicular to the carrying direction at the time of reflow, that is, if the carrying direction is horizontal in FIG. By doing so, the material of the printed wiring board can be saved, and the number of processing steps is reduced accordingly, which is economical.

FIG. 2 shows a cross section taken along the line AA in the embodiment of the printed wiring board shown in FIG. 1. This printed wiring board has a main body portion 1 and a discarding plate portion 2, and the inside thereof. Is composed of an insulating plate 11 and a pattern 12.
A metal reinforcing plate 4 is provided in the center of the insulating plate 11 of the discarding plate portion 2.
Is buried. The reinforcing plate 4 is sandwiched and embedded in the pressing step of laminating the insulating plates of the printed wiring board.

FIG. 3 shows a cross section of another embodiment of the printed wiring board. The difference from FIG. 2 is that the outer edge side of the reinforcing plate 6 embedded in the waste plate portion 5 is bent, and the sewing machine. The point is that the V groove 7 is provided instead of the eyes. Since the reinforcing plate 6 is bent on the outer edge side, the strength of the discarding plate portion is high.

FIG. 4 shows a cross section of an embodiment of a multilayer printed wiring board, which is a multilayer printed wiring board formed by stacking printed wiring boards 101 to 105 of first to fifth layers.
The main body portion 21 has a discard plate portion 22, and a reinforcing plate 24 is embedded in the center of the discard plate portion 22 of the third layer printed wiring board 103. The slit 23 corresponds to the slit 8 in FIG. 1, and the through hole 25 connects the patterns between layers. The reinforcing plate 24 is embedded in the manufacturing process of the third layer printed wiring board by the method described in FIG.

FIG. 5 shows a cross section of another embodiment of the multilayer printed wiring board, which is a multilayer printed wiring board formed by laminating printed wiring boards 201 to 205 of the first to fifth layers. 31 and a discard plate portion 32, and reinforcing plates 34 and 36 are embedded in the centers of the discard plate portion 32 of the second layer printed wiring board 202 and the fourth layer printed wiring board 204, respectively. The slit 33 corresponds to the slit 8 in FIG. 1, and the through hole 35 connects the patterns between layers. This example is characterized in that the strength of the waste plate portion is increased by having two reinforcing plates.

In each of the printed wiring boards and the multilayer printed wiring board described above, a metal reinforcing plate is embedded in the discarding plate portion, so that the warping strength of this portion is increased, and the printed wiring board or the reflowed wiring board is Warpage due to heat of the multilayer printed wiring board can be reliably suppressed.

[0029]

As described above, in the printed wiring board and the multilayer printed wiring board of the present invention, since the metallic reinforcing plate is embedded inside the discarding plate portion, the strength against warping of this portion becomes strong. At the time of reflow, it is not necessary to use a tool to prevent warpage, and the thickness of the waste plate part does not increase the thickness of the manufacturing process, which may interfere with the manufacturing process. This has the effect of completely preventing the warpage due to. Further, since the reinforcing plate can be embedded by a simple method, the cost can be reduced.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view taken along the line AA in FIG.

FIG. 3 is a cross-sectional view showing another embodiment of the printed wiring board of the present invention.

FIG. 4 is a sectional view showing an example of an embodiment of a multilayer printed wiring board according to the present invention.

FIG. 5 is a cross-sectional view showing another embodiment of the multilayer printed wiring board according to the present invention.

FIG. 6 is a cross-sectional view showing a conventional example.

FIG. 7 is a cross-sectional view showing another conventional example.

[Explanation of symbols]

1,21,31 body part 2, 22, 32 Discard part 3 perforations 4,6,24,34,36 Reinforcing plate 7 V groove 8,23,33 slits 11 Insulation plate 12 patterns 25,35 through holes

Claims (7)

[Claims] 1. A printed wiring board having a quadrilateral main body portion, which is a product portion, on which a wiring pattern is formed, and a non-product waste plate portion provided on an outer peripheral edge portion of the main body portion. The printed wiring board is characterized in that the plate portion is formed by embedding a metal reinforcing plate inside. 2. The printed wiring board according to claim 1, wherein the discarding board portion is provided only on two sides perpendicular to a conveying direction when a component is mounted on the main body portion and reflowed. . 3. The printed wiring board according to claim 1, wherein the reinforcing plate has a shape in which an outer edge side is bent. 4. A plurality of printed wiring boards, each of which has a quadrilateral body portion having a wiring pattern, which is a product portion, and a waste plate portion, which is provided outside the product and is provided on an outer peripheral edge portion of the body portion. In the multilayer printed wiring board described above, at least one layer of the printed wiring board is formed by embedding a metal reinforcing plate in the waste plate portion. 5. The multi-layer print according to claim 4, wherein the discard plate portion is provided only on two sides perpendicular to a conveying direction when a component is mounted on the main body portion and reflowed. Wiring board. 6. The printed wiring board according to claim 1, wherein the boundary between the main body portion and the discarding board portion is perforated for splitting. And multilayer printed wiring boards. 7. The boundary between the body portion and the discard plate portion is
The printed wiring board and the multilayer printed wiring board according to claim 1, 2, 3, 4 or 5, wherein a V groove for discarding is provided.