JP2012174823A - Mounting board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting board in which bending, shifting, floating, or the like, of an electronic component can be minimized for a printed circuit board without adjusting the amount of cream solder being applied to a land.SOLUTION: In a mounting board 1 where electrodes 30, provided at both ends of a light-emitting element substrate 12 in the longitudinal direction, are reflow soldered to a pair of lands 20, 20 formed on the surface of a printed circuit board 10, the light-emitting element substrate 12 is provided with an end face electrode on an end face formed by cutting four corners of a substantially rectangular substrate body 31 in the plan view. The land 20 includes a proximal part on which the lower surface electrode of the substrate body 31 is mounted, and extensions which extend from the positions corresponding to the end face electrodes, respectively, in the directions receding obliquely from the center line M of the light-emitting element substrate 12 in the longitudinal direction.

Description

  The present invention relates to a mounting board in which an electrode of an electronic component is soldered to a land portion formed on a surface of a printed board.

  In general, so-called surface mounting is known as a technique for mounting electronic components on a printed circuit board at a high density. In this surface mounting, a land portion of a conductor wiring is provided on the surface of a printed circuit board, cream solder is applied to the land portion using a mask, and an electrode of an electronic component is brought into contact with the land portion to which the solder paste is applied. Then, in this state, the printed circuit board on which the electronic component is placed is passed through a high-temperature furnace, and the solder of the electronic component is soldered (reflow soldered) to the land portion of the printed circuit board by melting the cream solder. It is formed (for example, see Patent Document 1). In surface mounting, it is not necessary to provide through holes for passing electronic component lead wires on the printed circuit board, so the strength of the printed circuit board can be maintained and high-density wiring and electronic components can be integrated on the printed circuit board. The mounting substrate can be reduced in size.

JP 2004-200194 A

However, in the conventional configuration, when soldering, the electrode of the electronic component is merely placed on the substantially rectangular land portion having the same shape as the bottom surface of this electrode via cream solder. When the cream solder melts, problems such as bending, misalignment, and floating of electronic components with respect to the printed circuit board may occur. As a technique for suppressing the bending, deviation, floating, etc. of these electronic components, it may be possible to reduce the thickness of cream solder applied to the land portion and reduce the amount of cream solder. Therefore, it is necessary to reduce the thickness of the mask. If the thickness of the mask is reduced as a whole, the amount of solder applied to the land portion of other electronic components is reduced, and the electronic components are joined. It will cause a decrease in strength.
Accordingly, the present invention has been made to solve the above-described problems, and suppresses bending, displacement, floating, etc. of electronic components with respect to the printed circuit board without adjusting the amount of cream solder applied to the land portion. An object of the present invention is to provide a mounting board that can be used.

  In order to achieve the above object, the present invention provides a mounting board in which electrodes provided at both ends in the longitudinal direction of an electronic component are reflow-soldered to a pair of land portions formed on the surface of the printed board. The electrode is provided on an end surface formed by cutting out four corners of a substantially rectangular main body in plan view, the land portion is connected to the base portion on which the end portion of the main body is placed, and the base portion, And an extending portion extending from the position corresponding to each electrode in a direction away from the longitudinal center line of the electronic component.

  In this configuration, the land portion may have a shape in which the extension portion is recessed toward the base side. Each of the electrodes may be formed in an arc shape of approximately ¼ circle in plan view. Further, the extending portion may be configured to extend in a direction connecting the arc center and the circle center of the electrode.

  According to the present invention, the land portion is connected to the base portion and includes the extending portions extending in directions away from the center line in the longitudinal direction of the electronic component. Therefore, the land portion extends from each electrode of the electronic component. When a solder fillet is formed along this direction, a tensile force is applied in the direction in which the fillet is formed. It is possible to correct misalignment, float, etc., and to suppress the occurrence of bending, misalignment, and float of electronic parts after reflow soldering.

It is a composition schematic diagram showing an optical sensor device provided with a mounting substrate concerning this embodiment. It is a top view which shows a mounting substrate. It is a trihedral view showing a light emitting element substrate. It is a top view which shows the land part formed in the printed circuit board. It is a top view which shows the tensile force which acts on a light emitting element board | substrate. It is a top view which shows the state which the light emitting element substrate moved to the reference position.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an optical sensor device including a mounting substrate according to the present embodiment. The optical sensor device 100 includes a pair of mounting substrates 1 and 2 that are arranged to face each other with a predetermined gap. These mounting boards 1 and 2 are printed circuit boards 10 and 11 on which conductive circuits are printed, and a light emitting element board 12 and a light receiving element board 13 as electronic components mounted on the opposing surfaces of these printed circuit boards 10 and 11, respectively. Is provided. In the present embodiment, light emitted from a light emitting portion (for example, a light emitting diode (LED)) 12A of the light emitting element substrate 12 is used as a light receiving portion (for example, a photodiode (photodiode)) 13A of the light receiving element substrate 13. When the oblique body 14 enters between the light emitting element substrate 12 and the light receiving element substrate 13, the above described light is blocked and the intrusion of the oblique body 14 is detected.
The light-emitting element substrate 12 and the light-receiving element substrate 13 are soldered to land portions (described later) formed on the surfaces of the printed boards 10 and 11, respectively, and reference numeral 15 in the figure denotes a fillet formed by soldering. It is.
In the optical sensor device 100 having such a configuration, the direction of the optical axis P of the light emitting portion 12A of the light emitting element substrate 12 is important. For this reason, in the mounting substrates 1 and 2 of this configuration, the light emitting element substrate 12 and the light receiving element substrate 13 can be soldered to a predetermined mounting position without bending, shifting, or floating with respect to the printed circuit boards 10 and 11, respectively. It is characterized in that

Next, the configuration of the mounting substrate 1 will be described. The mounting substrate 2 described above is different from the mounting substrate 1 in that the object to be mounted is the light receiving element substrate 13, but the structure for mounting the substrate is the same, and thus the description thereof is omitted.
FIG. 2 is a plan view showing the mounting substrate 1 according to the present embodiment, FIG. 3 is a three-side view showing the light emitting element substrate 12, and FIG. 4 shows a pair of land portions 20 formed on the printed circuit board 10. , 20 is a plan view.
As shown in FIG. 2, the mounting substrate 1 is formed by soldering electrodes 30, 30 formed at both ends of the light emitting element substrate 12 to a pair of land portions 20, 20 formed on the surface of the printed circuit board 10. Is done. A fillet 15 is formed on the land portions 20 and 20 by soldering.

As shown in FIG. 3, the light emitting element substrate 12 includes a substrate main body (main body) 31 formed in a substantially rectangular shape, and a light emitting portion 12 </ b> A is laminated and disposed at the center of the substrate main body 31. Further, the electrodes 30 are formed on both ends of the substrate body 31 in the longitudinal direction, respectively. The electrode 30 includes an upper surface electrode 30A, a lower surface electrode 30B, and an end surface electrode 30C in which a metal (for example, copper) film is formed on the substrate body 31 by plating. In the present embodiment, the four corners of the substrate body 31 are cut out into a circular arc shape of ¼ circle, and the end face electrode 30C described above is formed on this end face. The upper surface electrode 30A and the lower surface electrode 30B are electrically connected via the end surface electrode 30C, and the two end surface electrodes 30C and 30C arranged in the short direction of the substrate body 31 are electrically connected via the upper surface electrode 30A and the lower surface electrode 30B.
In addition, the end surface 31A of the substrate body 31 positioned between the two end surface electrodes 30C and 30C arranged in the short direction of the substrate body 31 is not formed with metal plating, and compared with the end surface electrodes 30C and 30C. The solder wettability of the end face 31A is lowered. Thereby, solder adheres to the end face electrodes 30C and 30 rather than the end face 31A, and fillets are more easily formed on the end face electrodes 30C and 30. In this case, when the fillet is formed, the solder acts to hold down the light emitting element substrate 12 by wetting up the end face electrodes 30C and 30 to prevent the light emitting element substrate 12 from floating from the printed circuit board 10. can do.
Further, since the end face electrodes 30C and 30C are formed by cutting out into a ¼ circular arc shape, fillets can be formed from the end face electrodes 30C in four different directions. For this reason, when a tensile force is applied in the forming direction of each fillet, self-alignment acts on the light emitting element substrate 12, and the light emitting element substrate 12 is corrected to bend, shift, and float. The tensile force refers to a force by which the end face electrodes 30C and 30C of the substrate body 31 are pulled by the action of the surface tension of the molten solder when the fillet is formed.

On the other hand, as shown in FIG. 2, the land portions 20, 20 are formed at positions corresponding to the electrodes 30, 30 of the light emitting element substrate 12 when the light emitting element substrate 12 is disposed at the reference position of the printed circuit board 10. ing. As shown in FIG. 4, these land portions 20, 20 have the same shape, and each land portion 20 is also symmetrical with respect to the longitudinal center line M of the light emitting element substrate 12. . On the land portion 20, cream solder 21 having substantially the same shape as the land portion 20 is applied by a method such as screen printing using a metal mask (not shown).
2 and 4, when the light emitting element substrate 12 is disposed at the reference position, the land portion 20 includes a base 20A that contacts the lower surface electrode 30B located at the end of the light emitting element substrate 12, and The base portion 20A is provided with extending portions 20B and 20B extending from each end face electrode 30C in a direction obliquely away from the longitudinal center line M of the light emitting element substrate 12 (X direction in the drawing).
In the present embodiment, as shown in FIG. 2, the extended portion 20B has an end face electrode 30C that is formed by cutting out a circular arc of a quarter circle when the light emitting element substrate 12 is disposed at the reference position. Is formed so as to extend in a direction (X direction in the figure) connecting the central portion 33A of the arc 33 and the center 34 of the circle. The direction connecting the central portion 33A of the arc 33 and the center 34 of the circle coincides with the formation direction of the fillet 15 in the arc 33 (end face electrode 30C). Generally, the tensile force applied in the formation direction of the fillet 15 increases as the length of the fillet 15 formed increases. For this reason, by extending the extending portion 20B in the direction in which the fillet 15 is formed, it is possible to increase the tensile force applied to the end face electrode 30C. Based on this tensile force, the light emitting element substrate 12 is bent and Misalignment can be corrected.

The land portion 20 includes a recess 20C that is recessed toward the base portion 20A between the extending portions 20B and 20B. The recess 20C is provided at a position corresponding to the end surface 31A of the substrate body 31 of the light emitting element substrate 12, and prevents the molten solder from flowing in the direction along the center line M in the reflow process. Therefore, the movement of the light emitting element substrate 12 in this direction is regulated. Further, in this configuration, since the land portion 20 includes the recess 20C, the distance between the contour of the recess 20C and the end surface 31A of the substrate body 31 can be shortened, so that solder is partially present in the vicinity of the end surface 31A. Thus, it is possible to prevent the formation of an indented solder indent, and for example, it is possible to prevent erroneous detection by an appearance inspection apparatus or the like.
The distance L2 between the land portions 20 and 20 is formed substantially the same as or slightly shorter than the distance L1 between the lower surface electrodes 30B and 30B of the light emitting element substrate 12, and the width W2 of the base portion 20A of the land portion 20 is the width of the lower surface electrode 30B. It is formed substantially the same as or slightly longer than W1, and when the light emitting element substrate 12 is arranged at the reference position, the electrodes 30, 30 of the light emitting element substrate 12 are surely positioned on the land portions 20, 20. ing.

Next, the effect | action concerning this embodiment is demonstrated.
FIG. 5 is a plan view showing a tensile force acting on the light emitting element substrate. As described above, the magnitude of the tensile force applied to the end face electrode 30C varies depending on the length of the fillet extending from the end face electrode 30C, that is, the length from the end face electrode 30C to the end of the extending portion 20B.
Therefore, as shown in FIG. 5, when the light emitting element substrate 12 is arranged in a state of being displaced with respect to the pair of land portions 20, 20, each end face electrode 30 </ b> C of the light emitting element substrate 12 is connected to the end face electrode 30 </ b> C. Tensile forces F1 to F4 act according to the length to the end of the extension 20B. Thereby, the light emitting element substrate 12 moves based on the magnitudes of the tensile forces F1 to F4 acting on the end face electrodes 30C. In FIG. 5, the tensile forces F1 and F2 acting on the respective end face electrodes 30C on the left side in the drawing are higher than the tensile forces F3 and F4 acting on the respective end face electrodes 30C on the right side in the drawing. Since it is large, the light emitting element substrate 12 moves to the left while rotating clockwise as a whole, and the positional deviation is corrected.
The light emitting element substrate 12 is moved until the tensile forces F1 to F4 are substantially balanced. When the tensile forces F1 to F4 are substantially balanced, as shown in FIG. The bending and deviation of the light emitting element substrate 12 are corrected at the reference position.

  Thus, according to the present embodiment, the mounting substrate in which the electrodes 30 provided at both ends in the longitudinal direction of the light emitting element substrate 12 are reflow soldered to the pair of land portions 20, 20 formed on the surface of the printed circuit board 10. 1, the light emitting element substrate 12 includes an end surface electrode 30 </ b> C on an end surface formed by cutting out four corners of a substantially rectangular substrate body 31 in plan view, and the land portion 20 includes the lower surface electrode 30 </ b> B of the substrate body 31. A base portion 20A to be placed, and an extension portion 20B extending to the base portion 20A and extending obliquely away from the longitudinal center line M of the light emitting element substrate 12 from positions corresponding to the end face electrodes 30C. When the solder fillet 15 is formed from each end face electrode 30C of the light emitting element substrate 12 to each extending portion 20B of the land portion 20, the fillet 15 is formed. Since the tensile force F1~F4 is applied to the direction, even as a mounting misalignment when mounting the light emitting element substrate 12 has occurred, the self-alignment works based on the difference in magnitude of the tensile force F1~F4 to the light-emitting device substrate 12. For this reason, even if it does not adjust the quantity of the cream solder apply | coated to the land parts 20 and 20, it becomes possible to correct | amend the light emitting element board | substrate 12, such as a curve, a shift | offset | difference, and a float, and the light emitting element board | substrate 12 after reflow soldering is possible. It is possible to suppress the occurrence of bending, deviation and floating.

  Further, according to the present embodiment, since the land portion 20 has a shape in which the extension portions 20B and 20 are recessed toward the base portion 20A, the melted solder is placed on the center line M in the reflow process. By preventing the flow in the direction along the direction, the movement of the light emitting element substrate 12 in this direction can be restricted.

  In addition, according to the present embodiment, the end face electrodes 30C and 30C are each formed in an arc shape of approximately ¼ circle in plan view, so that fillets are formed in four different directions from each end face electrode 30C. The self-alignment works on the light emitting element substrate 12 based on the tensile force acting in the formation direction of each fillet, and the light emitting element substrate 12 can be bent, displaced and lifted.

  In addition, according to the present embodiment, the extending portion 20B extends in a direction connecting the central portion 33A of the arc 33 of the end face electrode 30C and the center 34 of the circle, and therefore the tensile force applied to the end face electrode 30C is increased. It is possible to increase the size, and the bending and displacement of the light emitting element substrate 12 can be corrected based on the tensile force.

  The above embodiment is an aspect of the present invention, and it is needless to say that the embodiment can be appropriately changed without departing from the gist of the present invention. For example, the electronic component mounted on the light emitting element substrate 12 is described as the electronic component included in the mounting substrate 1 according to the present embodiment. However, the electronic component can be applied to other components as long as it is reflow soldered to the land portions 20 and 20. It doesn't matter.

1, 2 Mounting substrate 10, 11 Printed substrate 12 Light emitting element substrate (electronic component)
13 Light-receiving element substrate (electronic component)
15 Fillet 20 Land 20A Base 20B Extension 20C Recess 30 Electrode 30A Top Electrode 30B Bottom Electrode 30C End Electrode (Electrode)
31 Substrate body (main body)
31A End face 33 Arc 33A Center part 34 Center 100 Optical sensor device M Center line F1-F4 Tensile force

Claims (4)

In the mounting board where the electrodes provided at both ends in the longitudinal direction of the electronic component are reflow soldered to a pair of land portions formed on the surface of the printed board,
The electronic component includes the electrode on an end surface formed by cutting out four corners of a substantially rectangular main body in plan view, the land portion including a base portion on which the end portion of the main body is placed, and the base portion A mounting board comprising: extending portions extending in a direction away from a center line in a longitudinal direction of the electronic component from a position corresponding to each of the electrodes.   The mounting board according to claim 1, wherein the land part has a shape in which a space between the extending parts is recessed toward the base part side.   The mounting substrate according to claim 1, wherein each of the electrodes is formed in an arc shape of approximately ¼ circle in plan view.   The mounting board according to claim 3, wherein the extending portion extends in a direction connecting the arc center and the circle center of the electrode.

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