JP2015153990A - Connection structure of thin substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain solder workability while maintaining a land width and without reducing the quantity of inflow solders and to secure bond strength of the solder.SOLUTION: An upper-side thin substrate 23 is mounted on a lower-side thin substrate 21 (first thin substrate). Differently from a connection structure before improvement, inclined edges 24a cross each other on a land (first soldering land) 22 of the lower-side thin substrate 21. The land 22 of the lower-side thin substrate 21 is rectangular but the inclined edges 24a overlap each other on the land 22. Thus, lands 12 and 14 are conventionally brought into contact for a length of a shorter side but a land 24 is brought into contact with the land 22 in the rectangular shape on a diagonal line of the rectangular shape before notching. Thus, a distance of contact is made longer while keeping the equal length of the short side.

Description

  The present invention relates to a thin substrate connection structure in which two thin substrates are stacked and soldered.

With respect to the shape of the soldering land, those disclosed in Patent Documents 1 to 4 are known.
Patent Document 1 relates to a printed circuit board and a printed circuit board connection structure that provide a printed circuit board that takes a large fillet formation area and provides a space for storing excess solder to reduce soldering defects. In Patent Document 1, FIGS. 1 to 2 and paragraph 0014 indicate that “the first connection terminal 22a has a tapered shape that tapers toward the tip as shown in FIG. 1A”, paragraph. In addition, there is a disclosure that “the area of the fillet forming portion 62 can be increased and a space for storing excess solder can be provided”.

  Patent Document 2 relates to an electronic device in which a connection land formed on a first flexible substrate and a connection terminal formed on a second flexible substrate are arranged to face each other, and a manufacturing method thereof. In Patent Document 2, in FIG. 4, paragraph 0018, “the width of the connection terminal 3 is formed to be thinner than the width of the connection land 4. That is, the connection terminal 3 and the connection land 4 are soldered. In the region, the connection terminal 3 is formed to be smaller than the outer shape of the connection land 4.

  Patent Document 3 relates to a connection structure between printed circuit boards that obtains a connection structure between printed circuit boards that does not cause solder cracks or pattern peeling in the connection portion. In Patent Document 3, in FIG. 3 and paragraph 0017, “the connection form between the first printed circuit board 1 and the second printed circuit board 5 is as follows. It is disclosed that it is equivalent to mounting of general radial parts.

  Patent Document 4 discloses a wiring board for soldering each first wiring of a first wiring board and each second wiring of a second board so as to form a solder fillet having a good surface shape by a simple operation. Connection structure. In Patent Document 4, FIG. 5 and paragraph 0040 indicate that “the two overhanging portions 20 a and 20 b are extended to the tips of the overhanging portions 20 a and 20 b. Each of the extended portions 22a is formed in a slightly wider shape than each of the second wirings 22 ".

JP 2007-266070 A JP 2012-069599 A JP 2011-222826 A JP 2011-071230 A

With the miniaturization of products, the copper foil surface width (land width) of a flexible substrate (FPC) or a printed circuit board (PCB) is also reduced. When soldering, the reduced copper foil surface width naturally reduces the amount of solder flowing in, resulting in a problem that soldering workability deteriorates. Also, there is a problem that the bonding strength of the solder is weakened because the copper foil surface width is narrow.
In the above-described conventional Patent Documents 1 to 4, it is impossible to solve such problems that the amount of solder flowing in decreases and the solder workability deteriorates or the solder joint strength weakens.

  The present invention maintains solder operability without reducing the amount of solder flowing in while maintaining the land width, and ensures solder joint strength.

  The present invention corresponds to a first thin substrate having a plurality of first soldering lands formed on a surface thereof, and the first soldering land when overlaid on the first thin substrate. A second thin substrate having a plurality of second soldering lands formed on the surface of the portion adjacent to the edge and the second thin substrate on the surface of the first thin substrate. Connection of a thin substrate comprising solder portions that are soldered so as to straddle both the corresponding second soldering lands and the first soldering lands in a state in which the thin substrates are stacked. The structure is such that the edge of the second thin substrate is formed as an oblique edge so as not to be parallel to the parallel direction in which the second soldering lands are formed in parallel. .

  When the second thin substrate is stacked on the first thin substrate, the first soldering land on the surface of the first thin substrate and the portion in contact with the edge on the surface of the second thin substrate The plurality of second soldering lands formed so as to correspond to each other so that the edges of the second soldering lands are on the upper surface of the first soldering land. It is a positional relationship that touches. Conventionally, since the edge of the second thin substrate is arranged so as to be parallel to the arrangement direction of the first soldering lands, the width in the arrangement direction of the first soldering lands is effective. It became the width to become. In this state, the solder parts are soldered so as to straddle both the corresponding second soldering land and the first soldering land.

However, with the above configuration, the edge of the second thin substrate is formed with a skew edge, and the skew edge is formed in parallel with the second soldering land. It is formed so as not to be parallel to the direction. That is, even if the width of the land is the same, the contact is made on the hypotenuse, so that the distance of the solder portion can be increased even if the width is reduced.
In another aspect of the present invention, the skew edge is formed so as to be obliquely cut away with respect to the substrate edge of the second thin substrate.

In the above-described configuration, the distance of the solder portion can be increased by contacting with the oblique side even if the width of the same land is notched obliquely with respect to the substrate edge of the second thin substrate to be overlaid.
In another aspect of the present invention, the skew edge portion is formed by one notch formed so as to straddle both of the pair of second soldering lands adjacent on the second thin substrate. Has been.

The said structure WHEREIN: One notch is formed so that it may straddle both a pair of said 2nd soldering lands adjacent on a said 2nd thin board | substrate. Although the work for forming the cuts in the edge portions is only required once, it is formed so as to straddle both of the pair of adjacent lands, so that the oblique edge portions can be formed at a time for the two lands.
In another aspect of the present invention, the second thin substrate is formed to have an outer shape obliquely so as to be inclined with respect to an adjacent direction of the second soldering land, and the oblique edge portion has an outer shape. Is formed at the edge of the second thin substrate formed obliquely.

In the above configuration, the second thin substrate is inclined with respect to the adjacent direction of the second soldering land by forming the outer shape obliquely. Therefore, the skew edge is formed by the edge of the second thin substrate having an outer shape formed obliquely.
In another aspect of the invention, the first thin substrate and the second thin substrate are formed of a flexible substrate.
As an example, it is applied to a flexible substrate.

In another aspect of the invention, the skew edge is formed as a straight line.
In another aspect of the invention, the skew edge is formed in a curved shape.
In another aspect of the invention, the skew edge is formed in a crank shape.

According to the present invention, even if the width of the land is the same, it is possible to increase the distance of the solder portion by making contact with the hypotenuse, maintaining the land width and maintaining the solder workability without reducing the amount of solder flowing in. It becomes possible to ensure the solder joint strength.
That is, by making the joining side of the copper foil surface of a thin substrate such as an FPC inclined, the solder joining width can be increased without changing the size of the entire copper foil surface. Solder joint strength can be increased.

It is a top view of the 2nd thin substrate to which the connection structure of the thin substrate of this invention was applied. It is a top view of the 1st thin substrate to which the connection structure of the thin substrate of this invention was applied. It is a top view of the connection structure of the thin board | substrate of this invention. It is a top view of the 2nd thin substrate of the 2nd example. It is a top view of the connection structure of the thin substrate of a 2nd Example. It is a top view of the 2nd thin substrate of a 3rd example. It is a top view of the 2nd thin substrate of the 4th example. It is a top view of the 2nd thin substrate of a 5th example. It is a top view of the connection structure of the thin substrate of 5th Example. It is a top view of the upper thin board | substrate in the connection structure of the thin board | substrate before improvement. It is a top view of the lower thin substrate in the connection structure of the thin substrate before improvement. It is a top view of the connection structure of the thin board | substrate before improvement. It is sectional drawing of the process of superimposing the upper thin board | substrate on the lower thin board | substrate. It is sectional drawing of the state which mounted the upper thin board | substrate on the lower thin board | substrate, and was fixed by soldering.

(First Example)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing a second thin substrate to which the thin substrate connection structure of the present invention is applied, and FIG. 2 is a first thin substrate to which the thin substrate connection structure of the present invention is applied. 3 is a plan view, and FIG. 3 is a plan view showing the connection structure of the thin substrate of the present invention.
FIG. 10 is a plan view showing the upper thin substrate in the thin substrate connection structure before improvement, and FIG. 11 is a plan view showing the lower thin substrate in the thin substrate connection structure before improvement. FIG. 12 is a plan view showing a thin substrate connection structure before improvement.
Further, FIG. 13 is a cross-sectional view showing the process of superposing the upper thin substrate on the lower thin substrate, and FIG. 14 shows the soldering by placing the upper thin substrate on the lower thin substrate. The state fixed by attaching is shown by a sectional view.

  First, the situation before improvement will be described. Before the improvement, six rectangular lands 12 are formed in a horizontal line at a predetermined interval in the lower portion of the lower flexible substrate 11. The land 12 is formed on the surface of the flexible substrate 11 with a copper foil or the like as in the electric circuit, and is formed larger than the electric circuit. The lands 12 themselves are often formed mainly for connection with other circuit boards or for electrical connection with IC terminals or the like. The land 12 need not be formed along the edge of the lower flexible substrate 11.

  On the other hand, on the upper flexible substrate 13, six lands 14 having substantially the same width and the same interval as the land 12 are formed along the lower edge. As shown in FIG. 13, the upper flexible substrate 13 is overlaid on the lower flexible substrate 11 such that the lower edge thereof substantially overlaps the land 12 in the lower flexible substrate 11. At this time, the lands 14 of the upper flexible substrate 13 and the lands 12 of the lower flexible substrate 11 are aligned so as to overlap with each other so as to straddle both lands 12 and 14 manually as shown in FIG. Solder. Soldering This solder is called a solder part 15. The two flexible boards 11 and the flexible board 13 are fixed by the solder portion 15.

  Along with miniaturization of products, the area of FPC or PCB to be used tends to be reduced, and the width and pitch interval of the copper foil surface tend to be narrowed. In order to make the FPC and FPC (or PCB) conductive, the copper foil surfaces are soldered to each other. However, if the copper foil surface width becomes narrow, the amount of solder flowing in decreases, so that the solder becomes difficult to join. There was a problem that workability deteriorated. Further, since the width of solder bonding after soldering is narrow, there is a problem that the bonding strength is weakened and FPC can be removed when a strong force is applied.

  On the other hand, in the improved upper thin substrate (second thin substrate) 23 of the present invention shown in FIG. 1, the land (second soldering land) 24 arranged along the lower edge is wedge-shaped. The notch is formed. The notch is formed by connecting diagonals of the rectangular land 24 and cutting off a triangular portion surrounded by the oblique side, the short side, and the long side. Of course, the short side to cut off is on the lower edge side. This hypotenuse will be referred to as a skewed edge 24a. As a result, the lower edge of the upper thin substrate 23 has a saw blade shape in which the skewed edge portion 24a, the long side, and the lower edge portion between the lands 24 and 24 are repeated.

  The upper thin substrate 23 is placed on the lower thin substrate 21 (first thin substrate). The difference from before the improvement is that the skewed edge 24a intersects the land (first soldering land) 22 of the lower thin substrate 21. The land 22 of the lower thin substrate 21 has a rectangular shape, but the skew edge 24 a is overlapped on the land 22. In this way, while the lands 12 and 14 are in contact with each other with a short side length, they are in contact with the rectangular land 22 with a rectangular diagonal line before the land 24 is cut out. Despite the same side length, the tangent distance is longer.

Thus, the edge of the thin substrate 23 is not parallel to the parallel direction in which the lands (second soldering lands) 24 are formed in parallel (the direction parallel to the lower edge of the thin substrate 23). The portion is formed as a skewed edge portion 24a. Further, the skewed edge 24 a is formed so as to be cut out obliquely with respect to the substrate edge of the thin substrate 23.
As a result, when the copper foil surfaces are soldered to each other, the copper foil surface width becomes long and the amount of solder flowing in increases, so that the solder can be easily joined and the solder workability is improved. Further, since the width of solder bonding after soldering is wide, the bonding strength is increased, and it is possible to prevent the flexible substrate from being removed even when a strong force is applied.
In this embodiment and the following embodiments, the thin substrate is formed of a flexible substrate (also referred to as FPC). As with the flexible substrate, a general printed circuit board (PCB) may be used.

(Second embodiment)
FIG. 4 is a plan view showing a second thin substrate according to the second embodiment, and FIG. 5 is a plan view showing a connection structure of the thin substrate according to the second embodiment.
In the first embodiment, the cuts are formed for each land 24, but in the second embodiment, the oblique edges 34a, 34a are formed in the two lands 34, 34 by one cut. That is, the oblique edges 34a and 34a are formed by one notch formed so as to straddle both of the pair of adjacent lands 34 and 34 on the upper thin substrate 33. The notch has an isosceles triangle shape formed by the two oblique edges 34 a and 34 a and the lower edge of the thin substrate 33.
The direction of the oblique edge 34a is reversed for each land 34, and in the case of the second embodiment, the land 32 of the lower thin substrate 31 is in contact with the diagonal line of the land 34. Longer than.

(Third Example, Fourth Example)
In the second embodiment, since the notch is an isosceles triangle, the skew edge 34a is formed in a straight line shape. However, the shape of the notch can be changed.
6 and 7 show examples of notches of the third embodiment and the fourth embodiment.

  For example, in the case shown in FIG. 6, the notch on the land 44 is formed in a semicircular shape, and the thin substrate 43 is formed with a skewed edge portion 44 a having a curved shape.

7 is cut out in a rectangular shape so as to cover the land 54. When cut into a rectangular shape, the thin substrate 53 is formed with a skewed edge portion 54a having a crank shape. Even in such a crank shape, the relationship between the start point and the end point is arranged obliquely as compared with the straight line of the short side, so it can be said that the skew is broad.
In either case, the distance in contact with the lower land is longer than the width of the short side of the straight line, and the same effect can be obtained.

(Fifth embodiment)
FIG. 8 is a plan view showing a second thin substrate according to the fifth embodiment.
FIG. 9 is a plan view showing a connection structure of a thin substrate according to the fifth embodiment.
In the present embodiment, the upper thin substrate 63 is formed so that its outer shape is inclined so as to be inclined with respect to the adjacent direction of the land 64. That is, the lower edge 65 is skewed with respect to the adjacent direction of the land 64. Therefore, the oblique edge portion 64a is formed to coincide with the lower edge of the thin substrate 63 formed with an oblique outer shape.
In such a case, the lands 64 themselves are arranged obliquely along the inclined lower edge. Similarly, the lands 62 on the lower thin substrate 61 are also arranged obliquely at corresponding positions. Also in this embodiment, since the oblique edge portion 64a is formed longer than the width of the lands 62 and 64 in the short side direction, the same effect can be obtained.

Needless to say, the present invention is not limited to the above embodiments. It goes without saying for those skilled in the art,
-Applying the combination of the mutually replaceable members and configurations disclosed in the above-described embodiments as appropriate-The above-described embodiments are not disclosed in the above-described embodiments, but are publicly known techniques. The members and structures that can be mutually replaced with the members and structures disclosed in the above are appropriately replaced, and the combination is changed and applied. It is an embodiment of the present invention that a person skilled in the art appropriately replaces the members and configurations that can be assumed as substitutes for the members and configurations disclosed in the above-described embodiments, and changes the combination to apply. It is disclosed as.

DESCRIPTION OF SYMBOLS 11 ... Flexible substrate, 12 ... Land, 13 ... Flexible substrate, 14 ... Land, 15 ... Solder part, 21 ... Thin substrate, 22 ... Land, 23 ... Thin substrate, 24 ... Land, 24a ... Skew edge, 31 ... Thin substrate, 32 ... land, 33 ... thin substrate, 34 ... land, 34a ... skewed edge, 43 ... thin substrate, 44a ... skewed edge, 53 ... thin substrate, 54a ... skewed edge, 61 ... thin Substrate, 62 ... land, 63 ... thin substrate, 64 ... land, 64a ... skew edge, 65 ... lower edge.

Claims (8)

A first thin substrate having a plurality of first soldering lands formed on the surface;
A plurality of second soldering positions on the surface of the portion that is adjacent to the first soldering land when it is overlaid on the first thin substrate and is in contact with the edge. A second thin substrate on which lands are formed;
In a state where the second thin substrate is superposed on the surface of the first thin substrate, soldering is performed so as to straddle both the corresponding second soldering land and the first soldering land. A connection structure of a thin substrate comprising a solder portion to be made,
The thinness is characterized in that the second thin substrate is formed as an oblique edge so that the second soldering land is not parallel to the parallel direction formed in parallel. Board connection structure.   2. The thin substrate connection structure according to claim 1, wherein the skew edge is formed so as to be cut obliquely with respect to the substrate edge of the second thin substrate.   The skew edge portion is formed by one notch formed so as to straddle both of the pair of second soldering lands adjacent on the second thin substrate. The connection structure of the thin substrate according to claim 1 or 2. The second thin substrate is formed with a slanted outer shape so as to be inclined with respect to the adjacent direction of the second soldering land,
The thin board connection structure according to claim 1, wherein the skew edge portion is formed by an edge of the second thin board having an outer shape formed obliquely. The thin substrate connection structure according to any one of claims 1 to 4, wherein the first thin substrate and the second thin substrate are formed of a flexible substrate.   6. The thin substrate connection structure according to claim 1, wherein the skew edge is formed in a straight line shape.   6. The thin substrate connection structure according to claim 1, wherein the skew edge is formed in a curved shape.   6. The thin substrate connection structure according to claim 1, wherein the skew edge portion is formed in a crank shape.

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