JP2018041891A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board which can suppress the generation of a fault of soldering.SOLUTION: A circuit board 10 include a component insertion hole 11 into which a lead 21 of an electronic component 20 is inserted. An air vent hole 12 is formed over an inner area and an outer area of an area S with which a bottom face of the electronic component 20 is in contact so as to be across the area S. The air vent hole 12 is formed shorter than the length of the contour of the electronic component 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a circuit board.

  2. Description of the Related Art Conventionally, a circuit board (printed circuit board) on which an electronic component (inserted part) such as a capacitor is soldered using a soldering device (solder jet device) is known. In such a circuit board, a component insertion hole for inserting the lead of the electronic component and a gas vent hole communicating with the recess formed in the bottom of the electronic component are formed at a position where the electronic component is soldered. There is something to be done.

  And according to this circuit board, the gas which expand | swells in the space between a circuit board and the recessed part of an electronic component is discharge | released outside via a vent hole at the time of soldering. That is, in this circuit board, by suppressing the gas expanding in the space between the circuit board and the recess of the electronic component from moving outside through the component insertion hole, the lead of the electronic component and the component insertion hole This suppresses the occurrence of soldering defects.

JP 2002-84055 A

  However, in the circuit board described above, when the molten solder jet of the soldering apparatus is located below the gas vent hole, the molten solder may block the gas vent hole. In this case, the gas that expands in the space between the circuit board and the recess of the electronic component cannot be released to the outside through the vent hole. For this reason, in this case, the gas that expands in the space between the circuit board and the recess of the electronic component pushes down the molten solder from the component insertion hole, thereby causing poor soldering between the lead of the electronic component and the component insertion hole. May occur. Therefore, in the above circuit board, there is still a possibility that a soldering failure may occur during soldering.

  This invention is made | formed in view of such a situation, The objective is to provide the circuit board which can suppress generation | occurrence | production of the soldering defect.

  A circuit board that solves the above problem is a circuit board in which a component insertion hole into which a lead of an electronic component is inserted is formed, and an area inside the area so as to straddle an area where the bottom surface of the electronic component contacts A vent hole is formed over the outer region, and the vent hole is formed shorter than the outer length of the electronic component.

  When soldering an electronic component having a recess at the bottom with a soldering device, even if the lower part of the vent is blocked by molten solder, the electronic component on the circuit board is mounted in the vent. It is hard to be blocked by molten solder up to the side. For this reason, according to the above configuration, since the vent hole is formed so as to straddle the region where the bottom surface of the electronic component contacts, even if the lower portion of the vent hole is blocked by the molten solder, the circuit board and the electronic component It is easy to maintain the space between the outer space through the upper part of the vent hole. Therefore, even when the electronic component is soldered, even if the gas expands in the space between the circuit board and the electronic component, such gas is released to the outside through the vent hole. Further, as the molten solder rises in the air hole, the gas pushed up into the space between the circuit board and the electronic component is also released to the outside through the upper part of the air hole. Therefore, it is possible to suppress the gas in the space between the circuit board and the electronic component from pushing down the molten solder that is about to rise in the component insertion hole. As a result, it is possible to suppress the occurrence of poor soldering in the component insertion hole.

  In the circuit board, when the transport direction of the circuit board in the soldering apparatus is a substrate transport direction, the vent is preferably formed in a direction intersecting the substrate transport direction.

  The soldering apparatus performs soldering by transporting the circuit board in the board transport direction and passing the circuit board over the molten solder jetted. Here, the soldering apparatus may cause the molten solder to jet in a direction that is vertically upward, a direction that is between the vertically upward direction and the substrate transport direction, or a direction that is between the vertically upward direction and the opposite direction of the substrate transport direction. In many cases, the molten solder after reaching the highest point tends to flow in the substrate transport direction or in the direction opposite to the substrate transport direction.

  For this reason, if the air holes are formed in the board conveying direction, the molten solder is unlikely to hit the wall surface of the air hole intersecting the conveying direction, and may flow into the surface side of the circuit board through the air holes. In this case, on the surface of the circuit board, a solder ball is generated due to solidification of the molten solder, thereby causing a solder failure.

  On the other hand, according to the above configuration, since the air holes are formed in the direction intersecting the board conveying direction, the molten solder easily hits the wall surface of the air holes intersecting the board conveying direction, and the circuit board is formed via the air holes. It becomes difficult to flow into the surface side of the. Therefore, solder balls are hardly generated on the surface of the circuit board, and the occurrence of solder defects can be suppressed.

  The said circuit board WHEREIN: It is preferable that the said vent is formed in the direction orthogonal to the said board | substrate conveyance direction.

  According to the above configuration, when the vent hole is formed in a direction perpendicular to the board conveying direction, the molten solder is easy to surely hit the wall surface of the vent hole perpendicular to the board conveying direction, and is formed on the surface side of the circuit board through the vent hole. It becomes difficult to flow in. For this reason, solder balls are unlikely to occur on the surface of the circuit board, and the occurrence of solder defects can be suppressed.

  In the circuit board, it is preferable that the air holes are formed on an upstream side and a downstream side in the board transport direction.

  According to the above configuration, even when one vent hole is blocked by the molten solder, the other vent hole is not easily blocked by the molten solder. For this reason, air between the circuit board and the electronic component can be more reliably discharged to the outside regardless of the position of the molten solder of the soldering device with respect to the circuit board.

  In the circuit board, when the circuit board has a rectangular shape, the vent is preferably formed in a direction that forms an acute angle with a direction in which one side of the circuit board extends.

  Generally, the circuit board transport direction (board transport direction) in the soldering apparatus is a direction in which one side of the circuit board extends or a direction orthogonal to the direction in which one side of the circuit board extends. For this reason, in this case, the air holes are formed in the circuit board in an oblique direction with respect to the board conveyance direction. Therefore, solder balls are hardly generated on the surface of the circuit board, and the occurrence of solder defects can be suppressed.

Sectional drawing which shows the attachment structure of the circuit board which concerns on one Embodiment of this invention. The top view in the said circuit board. Explanatory drawing which shows a mode that a flux is apply | coated to the said circuit board. Explanatory drawing which shows a mode that soldering is carried out to the said circuit board. The top view of the circuit board in which the vent was formed in the board | substrate conveyance direction. FIG. 6 is a cross-sectional view taken along line GG in FIG. 5. The HH arrow directional cross-sectional view in FIG. The top view of the circuit board which concerns on a 1st modification. The top view of the circuit board concerning a 2nd modification. Sectional drawing of the circuit board which concerns on a 3rd modification. Sectional drawing of the circuit board which concerns on a 4th modification.

  Hereinafter, an embodiment of a circuit board will be described. In addition, the circuit board 10 of this embodiment shall be soldered with the flow type soldering apparatus.

  FIG. 1 is a cross-sectional view showing a mounting structure of a circuit board 10 according to an embodiment of the present invention, and is a cross-sectional view passing through the axis of a lead 21 of an electronic component 20. As shown in FIG. 1, the circuit board 10 has a component insertion hole 11, a vent hole 12, and a land 13.

  The electronic component 20 is, for example, an electrolytic capacitor, and has a recess 22 that is recessed on the bottom surface 23 side where the lead 21 is provided. The component insertion hole 11 is a hole for inserting the lead 21. The component insertion hole 11 is formed through the circuit board 10, and a land 13 for attaching solder is formed in the inner peripheral portion. When the lead 21 is inserted into the component insertion hole 11, the bottom surface 23 of the electronic component 20 comes into contact with the circuit board 10. When the surface of the circuit board 10 that contacts the bottom surface 23 of the electronic component 20 is the surface of the circuit board 10, the lead 21 protrudes from the component insertion hole 11 on the back surface of the circuit board 10. A space is formed between the surface of the circuit board 10 and the recess 22 of the electronic component 20. Thus, soldering is performed in a state where the electronic component 20 is arranged on the circuit board 10.

  FIG. 2 is a top view of the circuit board 10 in a region where the electronic component 20 is disposed. In FIG. 2, the transport direction of the circuit board 10 in the flow type soldering apparatus is assumed to be a substrate transport direction A. As shown in FIG. 2, the vent hole 12 is formed in the circuit board 10 so as to straddle the region S where the bottom surface 23 of the electronic component 20 contacts. The vent hole 12 penetrates the circuit board 10, but unlike the component insertion hole 11, no land is formed on the inner periphery.

  The vent hole 12 has a rectangular shape (rectangular shape) in a plan view of the circuit board 10. The longitudinal direction of the vent hole 12 is a direction orthogonal to the board conveyance direction A, and a direction orthogonal to the plate thickness direction of the circuit board 10. In this respect, in the present embodiment, it can be said that the air holes 12 are formed in a direction orthogonal to the substrate transport direction A.

  The length of the vent hole 12 in the longitudinal direction is shorter than the outer diameter (outer shape) of the electronic component 20. Specifically, the vent hole 12 is formed longer in the longitudinal direction by several millimeters (for example, 1 mm) on the inner side and the outer side than the region S where the bottom surface 23 of the electronic component 20 contacts. On the other hand, the length of the vent hole 12 in the short direction is formed to be about several mm (for example, 1 mm). Thus, the vent hole 12 is formed so as not to be blocked even when the flux is applied.

  Next, an operation when the electronic component 20 is soldered to the circuit board 10 of the present embodiment will be described.

  First, the circuit board 10 on which the electronic component 20 is mounted is fed into a flow type soldering apparatus. As shown in FIG. 3, a flux 51, which is a soldering accelerator, is applied to the back surface of the circuit board 10 from the application nozzle 50. After the flux 51 is applied, the entire circuit board 10 is heated by the heater.

  Subsequently, as shown in FIG. 4, the back surface of the circuit board 10 is immersed in the molten solder 52 that has been jetted, and soldering is performed. Here, even when the molten solder 52 comes into contact with the circuit board 10 so as to block the lower side of the vent hole 12 during soldering, the upper surface portion of the circuit board 10 of the vent hole 12 is melted. The solder 52 is not easily blocked. For this reason, even if the flux 51 is heated and gasified by the molten solder 52 and flows into the recess 22 between the circuit board 10 and the electronic component 20, the air and gas in the recess 22 are thermally expanded. Is discharged to the outside through the vent hole 12 (arrow B direction). Further, as the molten solder 52 rises in the vent hole 12, the air and gas pushed up into the recess 22 are also released to the outside through the vent hole (in the direction of arrow B). Therefore, since the molten solder 52 is not pushed down in the component insertion hole 13, the solder can be attached to both the land 13 and the lead 21.

  Subsequently, referring to FIGS. 6 and 7, the molten solder 52 that jets in the circuit board 10 </ b> A in which the air holes 12 </ b> A are formed in the board conveying direction A and the circuit board 10 of the present embodiment as shown in FIG. 5. The operation when the air vent 12 of the circuit board 10 passes through the upper part of the circuit board 10 will be described.

  6 is a cross-sectional view illustrating a state where soldering is performed on the circuit board 10A to be compared, and FIG. 7 is a diagram illustrating a state where soldering is performed on the circuit board 10 of the present embodiment. FIG. Further, as shown in FIGS. 6 and 7, it is assumed that the jetted molten solder 52 flows in the forward direction w1 or the reverse direction w2 with respect to the substrate transport direction A. 6 and 7, the electronic component 20 is not shown for easy understanding of the explanation.

  As shown in FIG. 6, when the vent hole 12A is formed in the substrate transport direction A, the substrate transport direction A is the longitudinal direction of the vent hole 12A. Therefore, when the vent hole 12A passes over the molten solder 52 that has been jetted, the molten solder 52 is unlikely to hit the wall surface of the vent hole 12A and is likely to rise to the surface side of the circuit board 10A through the vent hole 12A. That is, the molten solder 52 may flow into the surface side of the circuit board 10A. For this reason, when the molten solder 52 that has flowed into the surface side of the circuit board 10A is solidified, there is a possibility that a soldering defect such as a solder ball may occur.

  On the other hand, as shown in FIG. 7, when the vent hole 12 is formed in a direction orthogonal to the substrate transport direction A, the substrate transport direction A is the short direction of the vent hole 12. The length in the direction A is shorter than that shown in FIG. For this reason, when the vent hole 12 passes over the jetted molten solder 52, the molten solder 52 easily hits the wall surface of the vent hole 12, so that it rises to the surface side of the circuit board 10 through the vent hole 12. It becomes difficult. Therefore, according to this embodiment, generation | occurrence | production of the soldering defect is suppressed.

As described above in detail, according to the present embodiment, the following effects are obtained.
(1) Even when the molten solder 52 by the soldering device comes into contact with the lower surface of the vent hole 12, the air between the circuit board 10 and the electronic component 20 passes through the vent hole 12, and the electronic component 20 of the circuit board 10 is mounted. Is released to the outside. Therefore, generation | occurrence | production of the soldering defect can be suppressed.
(2) Since the air holes 12 are formed in a direction intersecting with the board conveying direction A, the molten solder 52 easily hits the wall surface of the air holes 12 intersecting with the board conveying direction A, and the circuit board 10 is interposed via the air holes 12. It becomes difficult to flow into the surface side of the. For this reason, solder balls are unlikely to occur on the surface of the circuit board 10, and the occurrence of solder defects can be suppressed.
(3) When the air holes 12 are formed in a direction orthogonal to the board conveying direction A, the molten solder 52 is easy to reliably hit the wall surface of the air holes 12 orthogonal to the board conveying direction A, and the circuit board 10 is interposed via the air holes 12. It becomes difficult to flow into the surface side of the. For this reason, solder balls are unlikely to occur on the surface of the circuit board 10, and the occurrence of solder defects can be suppressed.
(4) Since the length of the vent hole 12 in the longitudinal direction is shorter than the outer shape of the electronic component 20, a longer vent hole than the outer shape of the electronic component 20 is provided so as to straddle the region where the electronic component 20 is mounted. Compared with the case where it forms in, the strength fall of the circuit board 10 can be suppressed.

  In addition, you may change the said embodiment as shown below.

  In the embodiment described above, an electrolytic capacitor is used as the electronic component 20, but the present invention is not limited to this. The electronic component 20 may be another component having a recess on the bottom surface. Further, the electronic component 20 may be a prismatic electronic component. In this case, the longest length in the direction orthogonal to the height direction of the prismatic electronic component may be the length of the outer shape.

  Although the embodiment described above is soldered by the flow type soldering apparatus, it may be a dip type soldering apparatus.

  In the embodiment described above, the vent hole 12 is formed in a rectangular shape, but the present invention is not limited to this. The vent hole 12 may be a circle, an ellipse, or a polygon.

  In the embodiment described above, the air holes 12 are formed in a direction orthogonal to the substrate transport direction A, but the present invention is not limited to this. As shown in FIG. 8, the air holes 12 </ b> B may be formed in the circuit board 12 </ b> B in a direction intersecting with the board conveyance direction A. Further, as shown in FIG. 5, the air holes 12 </ b> A may be formed in the substrate transport direction A.

  Further, as shown in FIG. 9, the air holes 12C may be formed in a direction that forms an acute angle with a direction E in which one side of the rectangular circuit board 10C extends or a direction F in which another side orthogonal to the one side extends. . The vent hole 12C is formed in an oblique direction with respect to both the arrow E direction and the arrow F direction in FIG. The board conveying direction A of the circuit board 10C in the soldering apparatus is generally the arrow E direction or the arrow F direction. For this reason, in this case, the air holes 12 are formed in the circuit board 10C in an oblique direction with respect to the board conveyance direction A. Therefore, solder balls are hardly generated on the surface of the circuit board 10C, and the occurrence of solder defects can be suppressed. In addition, when the circuit board 10 on which the electronic component 20 is mounted is not rectangular, when the soldering is performed by the flow type soldering apparatus, the soldering is performed as the rectangular circuit board 10 together with the dummy board. Is common. Even in the above case, it may be formed in a direction in which one side of the rectangular circuit board 10 combined with the dummy substrate extends or in a direction that forms an acute angle with the direction in which the other side orthogonal to the one side extends.

  In the embodiment described above, one vent hole 12 is formed in the region S of the circuit board 10 where the bottom surface 23 of the electronic component 20 is in contact, but two or more holes may be formed.

  In this case, as shown in FIGS. 10 and 11, vent holes 12 a and 12 b may be formed on the upstream side B and the downstream side C in the substrate transport direction A. Specifically, as shown in FIG. 10, the vent holes 12a and 12b may be formed in the circuit board 10D with a space in the direction orthogonal to the board transport direction A. As shown in FIG. , 12b may be formed on the circuit board 10E with an interval in a direction crossing the substrate transport direction A. Further, in the substrate transport direction A, the distance between the air holes 12 a and the air holes 12 b is preferably longer than the length of the circuit boards 10 C and 10 D that are in contact with the jet of the molten solder 52.

  According to this, even when the air holes 12a formed on the upstream side B in the board transport direction A are closed by the molten solder 52 in the soldering by the flow type soldering apparatus, the board transport direction The vent hole 12 b formed on the downstream side C of A is not easily blocked by the molten solder 52. Even if the vent hole 12b formed on the downstream side C in the substrate transport direction A is closed by the molten solder 52, the vent hole 12a formed on the upstream side B in the substrate transport direction A is melted. It becomes difficult to be blocked by the solder 52. For this reason, air between the circuit boards 10D and 10E and the electronic component 20 can be more reliably discharged to the outside regardless of the position of the molten solder 52 of the soldering apparatus with respect to the circuit board 10.

10: Circuit board 11: Component insertion hole 12: Vent hole 12a: Vent hole 12b on the upstream side in the board transfer direction 13: Vent hole 13 on the downstream side in the board transfer direction 13: Land 20: Electronic component 21: Lead 22: Recess 23: Bottom surface 30: Solder 50: Coating nozzle 51: Flux 52: Molten solder A: Substrate transport direction B: Upstream side in the substrate transport direction C: Downstream side in the substrate transport direction E: Direction in which one side of the circuit board extends F: Circuit board Direction S in which one side extends: Area where the bottom surface of the electronic component contacts

Claims (5)

A circuit board in which a component insertion hole into which a lead of an electronic component is inserted is formed,
A ventilation hole is formed across the inner region and the outer region of the region so as to straddle the region where the bottom surface of the electronic component contacts.
The vent hole is a circuit board formed shorter than the outer length of the electronic component. When the circuit board transport direction in the soldering apparatus is the substrate transport direction,
The circuit board according to claim 1, wherein the vent hole is formed in a direction intersecting with the substrate transport direction.   The circuit board according to claim 2, wherein the vent hole is formed in a direction orthogonal to the substrate transport direction.   4. The circuit board according to claim 2, wherein the air holes are respectively formed on an upstream side and a downstream side in the board conveyance direction. 5. When the circuit board has a rectangular shape,
The circuit board according to claim 1, wherein the vent hole is formed in a direction that forms an acute angle with a direction in which one side of the circuit board extends.

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