JP2008181931A - Wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent unwanted solder adhesion to a wiring board except a portion to be soldered without causing deterioration in working performance. <P>SOLUTION: The wiring board 1 includes conductor layers 7 on both sides of a substrate core 5, and resist layers 9 as insulating layers on both the surfaces thereof, respectively, wherein lead terminals 11 of an electric component 3 are connected to a land portion 13 as electrodes of the conductor layers 7 exposed on an opening of the resist layer 9 via a solder 15. A large number of fine convex portions 21 are formed as an uneven portion 19 by the same method as that for the resist layer 9 or integrally formed in forming the resist layer 9 on the resist layer 9 near a connection portion 17 using this solder 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wiring board in which an electronic component is connected to a conductive portion by solder.

  When mounting electronic components on a wiring board, cream solder printing is performed on the wiring board, and after mounting the electronic components, soldering is performed in a reflow furnace, or by a jet of solder in the flow tank. The electronic component mounted on the top is soldered.

  In such a soldering process, the solder may adhere as a so-called solder ball in the form of a ball on the wiring board other than the connection portion by solder to the electronic component.

For such unnecessary solder such as solder balls, a method of removing the solder by a brush or air blow or a conductive pattern portion to be soldered on a wiring board as described in Patent Document 1 below. A method is known in which a masking agent is applied to an adjacent position to provide a masking portion, and after the soldering process, the masking portion is peeled off to remove solder balls attached to the masking portion together.
JP-A-5-235527

  However, even if a brush or air blow is used, it is not possible to sufficiently remove the solder adhered on the wiring board, and when a masking portion is provided, a step of peeling the masking portion after the soldering process is necessary. Workability deteriorates and productivity is reduced.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent unnecessary solder from adhering to a wiring board other than a part to be soldered without deteriorating workability.

  According to the present invention, during the soldering process, the solder generated on the wiring board other than the connection part by solder has a contact area with the wiring board by the uneven shape part provided on the surface provided with the connection part to the conductive part by solder. Since it becomes small, adhesion to a wiring board can be prevented. At this time, the conventional work such as peeling the masking portion after the soldering process is unnecessary, and the reduction in productivity can be prevented. Even if unnecessary solder adheres to the concavo-convex shape portion on the wiring board, the contact area of the solder with respect to the wiring substrate is reduced by the concavo-convex shape portion, so that it can be easily removed by a brush or air blow.

  In addition, by making the concavo-convex shape portions to be point-like with respect to the surface of the wiring board, the contact area with the solder can be made as small as possible, and solder adhesion can be more reliably prevented. And can be removed very easily.

  In addition, by removing the adhering solder by making the concavo-convex shape portion linear with respect to the surface of the wiring board, a brush or air blow is performed along the linear shape. As a result, the solder to be removed can be moved along the line shape, and the removal operation becomes easier.

  Furthermore, by forming the concavo-convex shape portion with an insulating protective layer, a special process is not necessary in manufacturing the wiring substrate, and the manufacturing cost can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1A is a sectional view showing a state in which an electronic component 3 is mounted on a wiring board 1 according to the first embodiment of the present invention, and FIG. 1B is a plan view thereof. The wiring board 1 here shows a part of it, but there is a board core 5 in the center, a conductor layer 7 made of copper foil is provided on both sides of the board core 5, and further on the conductor layer 7 for insulation The resist layer 9 is provided.

  On the other hand, in the electronic component 3, a plurality of lead terminals 11 are drawn from the side, and the lead end 11 a of the lead terminal 11 is used as a land as a conductive part that serves as an electrode of the conductor layer 7 without the resist layer 9. A connection portion 17 is formed by connecting and fixing to the portion 13 with solder 15.

  And the uneven | corrugated shaped part 19 is provided on the wiring board 1 (resist layer 9) of the above-mentioned connection part 17 periphery. That is, the wiring board 1 is provided with the concavo-convex shape portion 19 on the surface on the side provided with the connection portion 17 to the conductive portion (land portion 13) by the solder 15 of the electronic component 3.

  The concavo-convex portion 19 described above has a large number of fine hemispherical convex portions 21 formed on the resist layer 9. After the formation of the resist layer 9, the convex portions 21 are formed in a dot shape with respect to the surface of the wiring substrate 1 by a method similar to the formation of the resist layer 9 (for example, silk screen printing). Alternatively, when the resist layer 9 is formed, the convex portion 21 is formed as one integrated with the resist layer 9. By forming the convex portion 21, a concave portion 23 is formed between the convex portions 21, and the convex portion 21 and the concave portion 23 constitute the concave-convex shape portion 19.

  In addition, the above-described concavo-convex shape portion 19 has a sufficiently small size of the convex portions 21 and prevents the solder balls 25 to be described later from entering the concave portions 23 between the convex portions 21. It is narrow enough.

  When soldering the electronic component 3 to such a wiring board 1, after the cream solder printing is performed on the land portion 13, the electronic component 3 is mounted on the wiring board 1. At this time, the lead end 11 a of the lead terminal 11 is drawn. Is placed on the cream solder printing section, and soldering is performed in a reflow oven.

  Part of the solder that melts during the soldering process described above may be generated on the outside of the land portion 13 and move onto the uneven portion 19 as a solder ball 25. Here, as described above, in the concavo-convex shape portion 19, the size of the convex portion 21 is sufficiently fine and the interval between the convex portions 21 is sufficiently narrowed so that the solder ball 25 does not enter the concave portion 23. The solder ball 25 comes into contact only with the convex portion 21, and the contact area with respect to the wiring board 1 becomes small and it is difficult to adhere to the wiring board 1.

  Even if the solder ball 25 remains attached to the convex portion 21 of the concavo-convex shape portion 19, the contact area between the solder ball 25 and the concavo-convex shape portion 19 of the wiring substrate 1 is small as described above. Can be easily removed.

  As described above, in this embodiment, it is possible to prevent the solder balls 25 from adhering to the wiring board 1 simply by providing the concavo-convex portion 19 on the wiring board 1. At this time, the conventional masking member is peeled off. No work is required, and deterioration of workability can be prevented to prevent a decrease in productivity.

  Further, in the present embodiment, a large number of fine hemispherical convex portions 21 are formed as the concave and convex portion 19 so that the convex portions 21 are point-shaped with respect to the surface of the wiring board 1, thereby The contact area with the solder ball 25 can be reduced as much as possible, the adhesion of the solder ball 25 to the wiring board 1 can be more reliably prevented, and the removal when adhering is extremely easy.

  Furthermore, in the present embodiment, when the wiring board 1 is manufactured by providing the concave-convex shape portion 19 in the same manner as the resist layer 9 that is an insulating protective layer, or by being integrated with the formation of the resist layer 9. A special process is unnecessary, and the manufacturing cost can be reduced.

  FIG. 2 is a plan view of the wiring board 1 corresponding to FIG. 1B according to the second embodiment of the present invention. In the second embodiment, as the concavo-convex shape portion 27, a large number of linear convex portions 29 are provided in place of the many hemispherical convex portions 21 in the first embodiment. That is, in the uneven portion 27 here, the convex portion 29 is formed linearly with respect to the surface of the wiring board 1. Such a convex part 29 is formed by the same method as the convex part 21 in the first embodiment.

  The plurality of linear protrusions 29 described above extend in parallel to each other along the arrangement direction of the plurality of lead terminals 11 in the electronic component 3, and grooves 31 serving as recesses are formed between the protrusions 29. The concave-convex shape portion 27 is constituted by the portion 29 and the concave portion (groove 31).

  Here, the concave and convex portion 27 is formed so that the interval between the convex portions 29 is sufficiently narrow so that the solder balls 25 do not enter the grooves 31 and the contact area with the solder balls 25 is reduced. Is sufficiently narrow.

  Therefore, also in the second embodiment, the contact area of the solder ball 25 generated during the soldering process with respect to the wiring board 1 is reduced by the uneven portion 27, so that the solder ball 25 is difficult to adhere to the wiring board 1, and Even if it adheres, an effect similar to that of the first embodiment can be obtained, such as easy removal.

  Further, in the second embodiment, by removing the solder balls 15 attached to the concavo-convex shape portion 27 by making the convex portion 29 linear with respect to the surface of the wiring board 1, By applying a brush or carrying out air blow along the line, the solder ball 15 can be moved along the line, and the removal operation becomes easier.

  3 and 4 show an example in which the electronic component 3 is soldered in the reflow furnace shown in FIGS. 1 and 2 as described above, and soldered by a jet of solder using a flow tank. 1 and 2 are given the same reference numerals. 3A is a cross-sectional view corresponding to FIG. 1A, and FIG. 3B is a view as seen from the lower side of FIG. 3A. FIG. 4 is the same as FIG. 2 except that the concavo-convex portion 27 is the same as FIG.

  The wiring board 1 here has a through hole 1a penetrating in the thickness direction, and the lead terminal 11 of the electronic component 3 is inserted into the through hole 1a from below in FIG. 3A. A solder jet is sprayed, and the solder 15 sprayed connects the lead terminal 11 to the conductor layer 7 (land portion 13) exposed from the resist layer 9 around the through hole 1a and the conductor layer 33 in the through hole 1a. The connecting portion 17 is formed by being fixed.

  That is, the wiring board 1 here also has the uneven portion 19 on the surface of the electronic component 3 on the side provided with the connection portion 17 to the conductive portion (land portion 13) by the solder 15.

  In this example, as shown in FIGS. 3B and 4, on the lower surface in FIG. 3A opposite to the mounting surface of the electronic component 3 in the wiring board 1, Concave and convex portions 19 and 27 similar to those in FIG. 2 are provided throughout the resist layer 9.

  Here, in the concavo-convex shape portion 19 of FIG. 3B, a large number of hemispherical convex portions 21 are formed on the resist layer 9 as in the case of FIG. The concavo-convex shape portion 27 in FIG. 4 is formed with a large number of linear convex portions 29 on the resist layer 9 in parallel, similar to FIG. The convex portion 29 is formed linearly with respect to the surface of the wiring board 1.

  3 and 4, the contact area of the solder ball 25 generated during the soldering process with respect to the wiring board 1 is reduced by the uneven portions 19 and 27, so that the solder ball 25 adheres to the wiring board 1. The effects similar to those of the example of FIGS. 1 and 2 can be obtained.

  In the example of FIGS. 1 and 2, the concavo-convex portions 19 and 27 may be provided in the entire region of the resist layer 9 as in the examples of FIGS. 3 and 4, and conversely in the example of FIGS. As in the examples of 1 and 2, the concave and convex portions 19 and 27 may be provided around the periphery of the connection portion 17 (periphery).

(A) is sectional drawing which shows the state which mounted the electronic component on the wiring board concerning the 1st Embodiment of this invention, (b) is the top view. It is a top view of the wiring board corresponding to FIG.1 (b) concerning the 2nd Embodiment of this invention. (A) is sectional drawing of the wiring board in the case of performing a soldering process by a flow tank, (b) is a bottom view of (a). It is a bottom view at the time of making an uneven | corrugated shaped part linear with respect to FIG.

Explanation of symbols

1 Wiring board 3 Electronic component 13 Land part (conductive part)
15 Solder 17 Connection part 19, 27 Concave and convex part 21 Point-like convex part 29 Linear convex part

Claims (3)

  A wiring board in which an electronic component is connected to a conductive portion by solder, and a concave-convex shape portion is provided on a surface of the electronic component on a side provided with a connecting portion to the conductive portion by the solder. .   The wiring board according to claim 1, wherein the concavo-convex shape portion has a convex portion formed in a dot shape or a line shape with respect to the surface.   The wiring board according to claim 1, wherein the concavo-convex shape portion is formed of an insulating protective layer.

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