JP2012094681A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved printed wiring board which prevents rands for soldering which are exposed on a surface from peeling.SOLUTION: A printed wiring substrate is provided with rands 2 for soldering, for example, the rands 2 for soldering a number of terminals of an IC component, which are exposed on a surface. In the printed wiring substrate, a rand end part 2a which continues into a wiring pattern 3 and a rand end part on the opposite side are pressed with a printing paint 7 which is applied in silk printing. The rand end part 2a is pressed with the printing paint 7 so as not to peel. Thus, this structure prevents peeling of the rands 2.

Description

  The present invention relates to a printed wiring board to be incorporated into various electronic devices and the like, and more particularly to a printed wiring board improved so that a soldering land exposed on the surface does not peel off.

  As is well known, a soldering land for mounting various electronic components is exposed on the surface of the printed wiring board. Among such lands, a large number of lands arranged in order to solder a large number of terminals of an IC component have a narrow pitch and a small land area, so that the peel strength is inevitably insufficient.

On the other hand, as a prior art related to a land of a printed wiring board, a board provided with lands that radially have convex portions on the outer periphery of a circular portion for soldering circular components or the like (Patent Document 1),
A circuit board in which a concave portion is formed between a pair of lands and the outer peripheral edge of the land other than the opposing outer peripheral edge of the pair of lands is covered with a resist to prevent generation of a side ball (Patent Document 2) Or
A pair of soldering lands formed opposite to each other, a wiring connected to the soldering lands, a solder resist that covers the wiring, and an opening that exposes the soldering lands, and wiring only on the side facing the soldering lands And a printed wiring board (Patent Document 3) that can perform soldering satisfactorily even with small components by forming the opening outside the soldering land and inside the wiring,
A plurality of lands that connect the connection terminals of the IC package, a through hole that leads a conductive wire from this land to the opposite side surface of the substrate, and a through hole upper land provided around the same side of the through hole as the land A printed circuit board capable of mounting an IC package having a narrow terminal interval by decentering a through hole surrounded by a plurality of lands toward the land of the same potential connected to the upper land of the through hole (Patent Document 4) Or
A board provided with a soldering land part for soldering a cylindrical electrode terminal of a module component, the soldering land part having a concentric shape larger than the cylindrical electrode terminal and extending from the outer periphery In order to improve the positional accuracy and flatness of the electrode terminals connected by soldering, the plurality of protruding portions are evenly arranged on the outer periphery of the soldering land portion. Such a substrate (Patent Document 5) is known.

JP 2008-28811A JP 2007-329407 A JP 2007-80969 A JP 2006-165003 A JP 2004-55582 A

  However, the conventional printed wiring board provided with a large number of lands arranged for soldering a large number of terminals of the IC component has a narrow land pitch, a small land area, and a high peel resistance as described above. For example, if the heat is excessively applied when the IC component is replaced by melting solder, there is a problem that the land is peeled off from the printed wiring board.

  Such a problem of land peeling cannot be solved even with the techniques relating to the lands of Patent Documents 1 to 5.

  SUMMARY OF THE INVENTION The present invention has been made under the circumstances described above, and a problem to be solved is to provide an improved printed wiring board so that soldering lands exposed on the surface do not peel off.

  In order to solve the above problems, a printed wiring board according to the present invention is a printed wiring board provided with a soldering land exposed on the surface, and the end of the land is pressed with a silk-printed printing paint. It is characterized by.

  In the printed wiring board of the present invention, it is preferable that the land end opposite to the land end continuous with the wiring pattern is pressed with the printing paint.

  The land peeling prevention technology of the present invention is applied to all the lands provided on the surface of the printed wiring board. In particular, the land detachment preventing technique is applied to lands provided in a large number for arranging a large number of terminals of an IC component. On the other hand, it is applied very effectively.

  When the end of the land was pressed with silk-printed printing paint as in the printed wiring board of the present invention, too much heat was applied when replacing the electronic component whose terminals were soldered to the land. Even so, the land does not squeeze out from the end pressed by the printing paint, so that the land can be prevented from peeling off.

  In particular, it is the land end opposite to the land end continuous with the wiring pattern that is likely to bend when heat is applied excessively, and as described above, press the land end on the opposite side with printing paint. In addition, the printed wiring board can prevent the land from peeling off very effectively.

  Also, as described above, the lands provided in a large number for arranging a large number of terminals of the IC component are particularly easily peeled off, so that the print is made by pressing the end of the land for the IC component with printing paint. The wiring board has a particularly remarkable effect of preventing land peeling.

It is a partial top view of the printed wiring board concerning one embodiment of the present invention. It is sectional drawing along the AA line of FIG.

  Hereinafter, typical embodiments of the printed wiring board of the present invention will be described in detail with reference to the drawings.

  The printed wiring board shown in FIGS. 1 and 2 is formed by arranging a large number of lands 2 in two rows on the surface of the substrate body 1, and these lands 2 are respectively connected to the corresponding wiring patterns 3. ing. The land 2 and the wiring pattern 3 are formed by photo-etching a copper foil layer laminated on the surface of the substrate body 1, and the wiring pattern 3 is covered with a resist film 4. It is not exposed to the substrate surface.

  The land 2 is a land for joining a large number of terminals 5a protruding from both side surfaces of the IC component 5 (IC package) indicated by phantom lines with solder 6, and has the same pitch as the terminals 5a of the IC component 5. They are arranged in two rows on the left and right. As shown in FIGS. 1 and 2, each land 2 has a land end 2a opposite to the land end continuous to the wiring pattern 3 and is slightly extended in the opposite direction, so that the land area is increased accordingly. The extended land end 2a is pressed and reinforced by a silk-printed printing paint 7.

  That is, as shown in FIG. 2, from the surface of the resist film 4 formed between the lands 2 and 2 in the left and right rows, extended land end portions 2a of the lands 2 and 2 in the left and right rows are extended. The silk-printed printing paint layer 70 is formed so as to cover 2a, and the left and right lands 2, 2 are formed by the printing paint 7, 7 at both ends of the silk-printed printing paint layer 70. The extended land end portions 2a and 2a are pressed so as not to bend.

  In the printed wiring board of this embodiment, the land end 2a extended as described above is pressed by the silk-printed printing paint 7, so that when the IC component 5 is replaced, the terminal 5a and the land 2 are Even if heat is excessively applied to the portion joined by the solder 6, the land 2 does not swell from the land end 2a pressed by the printing paint 7, and the land area is increased by extending the land end 2a. Combined with the fact that the peel resistance of the land 2 is somewhat improved, it is possible to sufficiently prevent the land 2 from peeling. In addition, when the land end 2a is extended and pressed with the printing paint 7 as in the printed wiring board of this embodiment, the soldering area of the land 2 is not reduced.

  The place pressed by the printing material 7 printed with silk is not limited to the land end 2a opposite to the land end continuous with the wiring pattern 3, but for example, the land end continuous with the wiring pattern 3 or the side end of the land 2 Of course, the soldering area of the land 2 may be reduced, so that the soldering may be hindered. In addition, if the heat is applied excessively, it is easy to bend the wiring. Since it is the land end 2a opposite to the land end continuous to the pattern 3, even if only the land end 2a on the opposite side is pressed with the printing paint 7 as in the printed wiring board of this embodiment, Peeling can be prevented very effectively.

  In the printed wiring board of this embodiment, the end portions 2a of the lands 2 provided in a large number for arranging the numerous terminals 5a of the IC component 5 are pressed by the silk-printed printing paint 7. However, for a pair of lands that are provided opposite to each other for soldering and mounting an IC chip or other electronic component, or for a land that is provided independently, the land ends are similarly printed with silk-printed paint. Needless to say, it can be pressed to prevent peeling.

  In the printed wiring board of this embodiment, the printing paint layer 70 is formed by silk printing on the resist film 4 between the lands 2 and 2 in the left and right columns, and the land is formed with the printing paint 7 at both ends thereof. Although the end 2a is pressed, the printing paint layer 70 is formed by silk printing directly on the surface of the substrate body 1 without forming the resist film 4 between the lands 2 and 2, and the printing paint 7 at both ends thereof is formed. Of course, the land end 2a may be pressed.

DESCRIPTION OF SYMBOLS 1 Board | substrate body 2 Land 2a The extended land edge part on the opposite side to the land edge part which continues to a wiring pattern 3 Wiring pattern 4 Resist film 5 IC component (IC package)
5a IC component terminals 6 Solder 7 Printing paint 70 Printing paint layer

Claims (3)

  A printed wiring board provided with soldering lands exposed on the surface, wherein an end of the land is pressed with a silk-printed printing paint.   The printed wiring board according to claim 1, wherein a land end opposite to a land end continuous with the wiring pattern is pressed with the printing paint.   3. The printed wiring board according to claim 1, wherein the lands are lands arranged in a large number for soldering a large number of terminals of an IC component.

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