JP2007109970A - Printed wiring board and its connection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board capable of suppressing occurrence of a solder bridge between connection terminal parts each other, capable of securing bonding strength between the connection terminal and an insulating substrate, and also, capable of preventing occurrence of defects at a connection. <P>SOLUTION: Solder reservoir recesses 7 are respectively recessed toward the insulating substrate 2 from a soldering scheduled face of the connection terminal 3A, and whose plane shape on the soldering scheduled face has a contour of being surrounded by a closed curved line. The recesses are formed to the connection terminal 3A along in a wiring length direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printed wiring board used for electric / electronic devices and a connection structure thereof, and more particularly to a printed wiring board provided with a terminal portion connected by soldering.

  As a method of connecting the printed wiring boards, there is a method of soldering connection terminal portions of a pair of printed wiring boards. Specifically, a solder layer is provided on the surface of the connection terminal portion of at least one printed wiring board of the pair of printed wiring boards, and a flux for promoting soldering is further applied to connect the connection terminals of both printed wiring boards. The parts are superposed and connected by applying pressure while heating at a predetermined temperature. FIG. 17 shows a state in which the connection terminal portions 103 and 104 formed at the same pitch on the pair of printed wiring boards 101 and 102 are soldered.

  In recent years, the wiring patterns of printed wiring boards have been miniaturized and fine pitches have been developed. Due to excessive soldering during soldering, a solder bridge 106 as shown in FIG. 17 is generated and adjacent wirings are short-circuited. As a result, wiring failure occurs. Moreover, as a cause of facilitating the formation of the solder bridge 106, there is an action of blowing off the melted solder due to the rapid evaporation of the gas generated from the spear component by heating the flux used for soldering or the alcohol that is the solvent of the spear component. .

  As a structure for preventing the formation of such a solder bridge, as shown in FIGS. 18 and 19, it extends in the length direction at the center in the width direction of the connection terminal portion 203 in one printed wiring board 201. A device in which a slit 205 opened at the leading edge is formed is known (see, for example, Patent Document 1). The other printed wiring board 202 uses a connection terminal portion 204 in which no slit is formed. The slit 205 has a function of releasing the vapor generated by heating the flux and the alcohol that is the solvent of the spear component from the open portion of the tip edge when the solder is soldered.

In this way, when the printed wiring board 201 having the connection terminal portion 203 in which the slit 205 is formed and the printed wiring board 202 having the connection terminal portion 204 in which the slit 205 is not formed are soldered, as shown in FIG. The fillet 206 is formed on the outer wall surface of the connection terminal portion 203 and the connection terminal portion 204, and the fillet 207 is also formed on the inner wall of the slit 205.
Japanese Patent Laid-Open No. 9-46031 (paragraph 0019, FIG. 3)

  However, at the open end portion of the slit 205 of the connection terminal portion 203, gas and vapor are concentrated and blown out. For example, when molten solder is blown off along the oblique arrow a shown in FIG. There is a possibility that solder bridges may be formed between the 204 and between the connection terminal portions 203.

  Further, at the tip end portion of the connection terminal portion 203 where the slit 205 is opened (indicated by an ellipse b in FIG. 18), the bonding area between the connection terminal portion 203 and the insulating substrate (see FIG. 19) 201A of the printed wiring board 201. However, since it becomes smaller by the amount of the slit 205 formed, there is a problem that the tip portion of the connection terminal portion 203 is easily peeled off from the insulating substrate 201A. In addition, not only the front end portion of the connection terminal portion 203 but also the entire area where the slit 205 is formed in the connection terminal portion 203, the connection area with the insulating substrate 201 </ b> A is the connection terminal portion corresponding to the area where the slit 205 is formed. The length is uniformly reduced in the length direction 203. For this reason, there is still a problem that the connection terminal portion 203 is easily peeled off from the insulating substrate 201A. In addition, when at least one of the printed wiring boards 201 and 202 is a flexible printed wiring board having flexibility, the distal end of the connection terminal portion 203 that the slit 205 opens as the flexible printed wiring board bends repeatedly. There is a possibility that the insulating substrate 201A may be peeled off from the portion.

  Further, in the connection structure of the wiring terminals, one slit 205 is formed in the center in the width direction of the connection terminal portion 203 along the length direction of the wiring, and the fillet 207 formed on the inner wall of the slit 205 is formed. This has the effect of increasing the connection strength with the connection terminal portion 204 of the other printed wiring board 202, but since the joint area corresponding to the area of the slit 205 is reduced, the connection surface between the connection terminal portions 203 and 204 is There was a problem that the connection resistance increased.

  The above-described problems become more serious as the wiring pattern of the printed wiring board becomes finer and finer.

  The object of the present invention is to suppress the occurrence of solder bridges between the connecting terminal portions, and to increase the bonding strength, to ensure the bonding strength between the connecting terminal portion and the insulating substrate, resulting in defective connection portions. An object of the present invention is to provide a printed wiring board that is difficult to perform and a connection structure thereof.

  Another object of the present invention is to provide a printed wiring board in which an increase in connection resistance between connecting terminal portions of a pair of printed wiring boards is suppressed, and a connection structure thereof.

  Therefore, a first feature of the present invention is a printed wiring board, having a connection region in which connection terminal portions of a plurality of wirings are arranged at intervals on at least one surface of an insulating base material, A solder reservoir having a contour that is recessed in the terminal part from the planned soldering surface of the connection terminal part toward the insulating substrate along the wiring length direction, and whose planar shape on the planned soldering surface is surrounded by a closed curve The gist is that a recess is formed.

  In the invention according to the first feature, it is preferable that the connection terminal portion has a plurality of the solder reservoir recess portions formed intermittently along the wiring length direction. Further, it is preferable that a solder plating layer not using flux (non-flux) is formed on the soldering planned surface of the connection terminal portion. The planar shape of the solder reservoir recess is not limited, but is preferably selected from a polygon, a circle, and an ellipse. Further, the solder reservoir recess and the depth in the minimum region formed along the wiring length direction of the connection terminal portion and including the outlines of the two solder reservoir recesses at both ends in the length direction among the plurality of solder reservoir recesses. Are assumed to be the virtual recesses, the total area of the inner walls of the plurality of solder reservoir recesses is preferably larger than the total area of the inner walls of the virtual recesses.

  A second feature of the present invention is a printed wiring board connection structure, in which a plurality of wiring connection terminal portions are arranged at intervals on a pair of printed wiring boards, and are joined to each other in the pair of printed wiring boards. A connecting structure in which the connecting terminal portions are soldered to each other, and is insulative from the soldering surface of the connecting terminal portion to one connecting terminal portion of the pair of printed wiring boards along the wiring length direction. A solder reservoir recess is formed with a contour that is recessed toward the surface and the planar shape of the soldering surface is surrounded by a closed curve, and the connecting terminal portions that are joined together store solder on the inner wall of the solder reservoir recess. And a fillet is formed on the outer walls of the connection terminal portions.

  In the invention according to the second feature, it is preferable that a plurality of solder reservoir recesses be formed along the length direction of the connection terminal portion. Further, when at least one of the pair of printed wiring boards has flexibility, the application of the present invention is particularly effective. The planar shape of the solder reservoir recess is not limited, but is preferably selected from a polygon, a circle, and an ellipse. Further, among the plurality of solder reservoir recesses formed along the wiring length direction of the connection terminal portion, the solder reservoir recesses and the depths of the solder reservoir recesses are defined in a minimum region including the outlines of the two solder reservoir recesses at both ends in the length direction. It is preferable that the total area of the inner side walls of the plurality of solder reservoir recesses is set to be larger than the total area of the inner side walls of the virtual recesses when assuming the recesses having the same height as the virtual recesses.

  According to the first aspect of the invention, for example, when the connection terminal portion is soldered to the mating connection terminal portion of the mating printed wiring board that is the connected object, it is possible to suppress the occurrence of a solder bridge. .

  According to the first aspect of the invention, since the outline of the solder reservoir recess is surrounded by a closed curve, the total length and area of the fillet forming portion that connects between the counterpart wiring terminal and the wiring terminal is Since it becomes large, joint strength with the other party wiring terminal can be enlarged.

  According to the first aspect of the invention, since the outline of the solder reservoir recess is surrounded by a closed curve, that is, the tip of the connection terminal portion has the soldering surface of the connection terminal portion. It is possible to ensure the soldering strength between the distal end portion of the portion and the counterpart wiring terminal, and also ensure the bonding strength between the distal end portion of the connection terminal portion and the insulating substrate. For this reason, the printed wiring board which cannot produce the defect of a connection part easily is realizable.

  According to the first aspect of the invention, it is possible to realize a printed wiring board in which an increase in connection resistance with the counterpart wiring terminal is suppressed.

  In addition, according to the invention relating to the second feature, it is possible to suppress the occurrence of a solder bridge between the connection terminal portions, the bonding strength is large, and the bonding strength between the connection terminal portion and the insulating substrate can be ensured. Thus, it is possible to obtain a connection structure of a printed wiring board having durability that is unlikely to cause a defective connection portion.

  According to the second aspect of the invention, an increase in connection resistance between the connection terminal portions of the pair of printed wiring boards can be suppressed.

  Hereinafter, the details of the printed wiring board and the connection structure thereof according to the embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic and the thicknesses and ratios of the material layers are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Configuration of printed wiring board)
1 to 3 show a printed wiring board 1 according to the present embodiment. 1 is a plan view showing the main part of the printed wiring board 1, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line BB in FIG.

  The printed wiring board 1 includes an insulating substrate (base material) 2, a plurality of wirings 3 patterned on one surface of the insulating substrate 2, and an insulating substrate 2 on which these wirings 3 are formed. And a resist layer (cover layer) 5 formed on the adhesive layer 4.

  As the insulating substrate 2, for example, a flexible substrate made of polyimide resin, liquid crystal polymer, or the like can be used. In this embodiment, the insulating substrate 2 is a flexible flexible substrate, but may be a rigid substrate made of a prepreg such as a glass epoxy resin.

  The wiring 3 is formed by patterning a copper foil attached on the insulating substrate 2 by, for example, a subtractive method. As the adhesive layer 4, for example, various resin adhesives such as polyimide, epoxy, and olefin can be used. As the resist layer 5, for example, a polyimide resin or the like can be used similarly to the insulating substrate 2.

  The printed wiring board 1 includes a connection region 6 at a predetermined end portion of the insulating substrate 2 where the connection terminal portions 3A of the plurality of wirings 3 are exposed. As shown in FIG. 1, these connection terminal portions 3A are arranged at the same pitch so as to be parallel to each other.

  In each connection terminal portion 3A, four solder reservoir recesses 7 are arranged at a predetermined interval along the wiring length direction at the center in the width direction of the connection terminal portion 3A. As shown in FIG. 1, the solder reservoir recess 7 has a rectangular shape in which the shape on the planned soldering surface (the upper surface of the connection terminal portion 3 </ b> A) is a closed curve. Moreover, in this Embodiment, the depth of the solder reservoir recessed part 7 is the same as the thickness dimension of the wiring 3, and is set to the depth which the insulating base material 2 exposes. Incidentally, such a method of processing the solder reservoir recess 7 is such that when the wiring 3 is patterned by the subtractive method, the solder reservoir recess 7 is formed in the photomask for exposure so that the solder reservoir recess 7 can be etched simultaneously. What is necessary is just to add and set the pattern for forming.

  Since the solder reservoir recess 7 has a planar shape surrounded by a closed curve, the tip portion 3A1 of the connection terminal portion 3A is joined to the insulating substrate 2 over the entire width dimension of the connection terminal portion 3A. Is expensive. Similarly, the portions 3A2, 3A3, 3A4 between the solder reservoir recesses 7 in the connection terminal portion 3A are also bonded to the insulating substrate 2 over the entire width dimension of the connection terminal portion 3A, so that the adhesion strength is increased. And has an effect of preventing the connection terminal portion 3A from peeling off from the insulating substrate 2.

  In order to solder the printed wiring board 1 having such a configuration to another printed wiring board, a solder plating layer may be formed on the surface of the connection terminal portion of at least one of the printed wiring boards. As the solder plating layer, it is desirable to use a solder material that can be soldered without using a flux.

(Printed wiring board connection structure)
Next, a printed wiring board connection structure according to the present embodiment will be described with reference to FIGS. In the present embodiment, the printed wiring board 1 and the flexible printed wiring board 10 are soldered, and the solder reservoir recess 7 is formed in the connection terminal portion 3A on the printed wiring board 1 side. In this example, the solder terminal recess is not formed in the connection terminal portion 12A of the other printed wiring board 10. However, in the present invention, it is also applicable to a configuration in which a solder reservoir recess is formed in both connection terminal portions of the printed wiring boards that are connected to each other.

  The printed wiring board 10 has substantially the same configuration as the printed wiring board 1 described above, and an insulating substrate 11, a plurality of wirings 12 patterned on one surface of the insulating substrate 11, and these wirings 12 are formed. An adhesive layer 13 formed on the insulating substrate 11 and a resist layer (cover layer) 14 formed on the adhesive layer 13 are provided. As the insulating substrate 11, similarly to the insulating substrate 2, a flexible substrate made of, for example, a polyimide resin or a liquid crystal polymer is used. The width dimension and interval of the connection terminal portion 12A are set to be the same as those of the connection terminal portion 3A of the printed wiring board 1.

  Then, a non-flux solder plating layer is formed on at least one of the connection terminal portions 3A and 12A in the connection region of the pair of printed wiring boards 1 and 10, and soldering is performed by applying a predetermined temperature and pressing force. It has been subjected. As shown in FIGS. 5 and 6, the solder 15 formed in a fillet shape connecting the connection terminal portions 3 </ b> A and 12 </ b> A is formed in the solder reservoir recess 7 along the inner wall by such soldering. It is accumulated. Moreover, as shown in FIG. 6, the fillet 15A is formed in the outer wall of the connection terminal portions 3A and 12A.

  In the connection structure of the printed wiring board of the present embodiment, the solder 15 accumulates in the solder reservoir recess 7 formed in the connection terminal part 3A of the printed wiring board 1, so that the connection terminal parts 3A adjacent to each other or the connection terminal parts It can suppress that a solder bridge is formed between 12A.

  Further, in the printed wiring board connection structure of the present embodiment, the front end portion 3A1 of the connection terminal portion 3A of the printed wiring board 1 is bonded to the insulating substrate 2 at the portion surrounded by the ellipse d in FIG. Therefore, as shown in FIG. 7, even when the counterpart printed wiring board 10 is bent in the direction of the arrow c as shown in FIG. 7, the tip portion 3A1 of the connection terminal portion 3A (in FIG. The portion surrounded by e) is difficult to peel off from the insulating substrate 2. Similarly, the tip portion 3A1 of the connection terminal portion 3A of the printed wiring board 1 is soldered to the connection terminal portion 12A of the counterpart printed wiring board 10 in the full width, so that the connection portion with the connection terminal portion 12A Is difficult to peel off.

  As described above, in the printed wiring board connection structure according to the present embodiment, the bonding strength between the connection terminal portion 3A and the mating connection terminal portion 12A is large, and the tip portion 3A1 of the connection terminal portion 3A and the insulating substrate 2 are connected. In addition, it is possible to obtain a connection structure having durability in which the connection strength between the two can be ensured and the connection portion is less likely to be defective.

  Further, in the printed wiring board connection structure according to the present embodiment, the solder 15 accumulates in the solder reservoir recess 7, and this solder 15 also contributes to the connection. Therefore, the connection resistance between the connection terminal portions 3 </ b> A and 12 </ b> A is increased. Can be suppressed.

  Furthermore, the printed wiring board connection structure according to the present embodiment is particularly effective for connection between thin and narrow pitch printed wiring boards, which are becoming lighter and thinner in recent years. The reason for this is that along with miniaturization of the connection terminal part, suppression of solder bridge generation and non-flux soldering are desired, and connection strength and connection durability are also desired for the fine connection terminal part. Because. Incidentally, the specific thickness dimension of the printed wiring board and the pitch of the connection terminal portions are as follows. That is, the insulating substrates 2 and 11 have a thickness of 12 to 50 μm, the wirings 3 and 12 have a thickness of 5 to 35 μm, the adhesive layers 4 and 13 have a thickness of 15 to 50 μm, and the resist base layers 5 and 14. The thickness dimension is 12 to 50 μm, the thickness dimension of the solder plating layer is 1 to 10 μm, the pitch of the connection terminal portion is 100 μm, and the depth dimension of the connection terminal portion is about 2 mm.

  As described above, in this embodiment, four rectangular solder reservoir recesses 7 are intermittently arranged in the wiring length direction in the connection terminal portion 3A. However, the planar solder reservoir recesses may be surrounded by a closed curve. For example, the number may be singular or plural.

  Next, when the solder reservoir recesses are formed in the connection terminal portion T using FIG. 8, the total number of solder reservoir recesses and the side wall surfaces of the connection terminal portion T (the side surfaces in the wiring width direction and the inner sidewalls of the solder reservoir recesses). The area will be described.

  FIG. 8A shows a connection terminal portion T as a comparative example. In this comparative example, the length dimension D is 2000 μm, the width dimension W is 300 μm, and the thickness dimension is 35 μm. Further, with respect to such a connection terminal portion T, a connection terminal portion T1 as shown in FIG. 8B is formed by forming one solder reservoir recess H1. The solder reservoir recess H1 has a length dimension D1 of 1900 μm, a width dimension W1 of 100 μm, and a dimension D3 from the solder reservoir recess H1 to the edge in the length direction of the connection terminal portion T is 50 μm. Furthermore, with respect to the connection terminal portion T, the connection terminal portion T2 as shown in FIG. 8C has two solder reservoir recesses H2. This solder reservoir recess H2 has a length dimension D2 of 950 μm, a dimension D4 between the solder reservoir recesses H2 of 50 μm, and the other dimensions are the same as those of the solder reservoir recess H1.

The total area of the side wall surfaces of the connection terminal portion T shown in FIG. 8A is 161000 μm ² (W × t + D × t) × 2. The total area of the side wall surface of the connection terminal portion T1 shown in FIG. 8B is (W × t + D × t) × 2 + (W1 × t + D1 × t) × 2, which is 301000 μm ² . The total area of the side wall surfaces of the connection terminal portion T2 shown in FIG. 8C is (W × t + D × t) × 2 + ((W1 × t + D2 × t) × 2) × 2, which is 304,500 μm ² .

  As described above, the connection terminal portion T1 is formed with one solder reservoir recess H1, so that the total area of the side wall surface is larger than that of the connection terminal portion T where the solder reservoir recess H1 is not formed, thereby forming a solder fillet. The area provided for is increased. Further, since the connection terminal portion T2 has two solder reservoir recesses H2, the total area of the side wall surface is larger than that of the connection terminal portion T and the connection terminal portion T1, and the area used for forming the solder fillet is small. growing. 9 is a cross-sectional view in the width direction showing a state where the connection terminal portions T shown in FIG. 8A are soldered to each other, and FIG. 10 is a connection terminal portion shown in FIG. 8B or 8C. It is sectional drawing of the width direction which shows the state which soldered T1 or connecting terminal part T2. As shown in FIG. 9, in the soldering of the connection terminal portions T in which the solder reservoir concave portions are not formed, the amount of fillets formed by escaping to the side wall in the width direction becomes large, and the connection terminal portions of the adjacent ones may be The possibility that a solder bridge is formed between T increases. On the other hand, as shown in FIG. 10, in the connection terminal portion T1 or the connection terminal portion T2 in which the solder reservoir recess H1 or the solder reservoir recess H2 is formed, the solder 15 is also formed as a fillet on the side wall in the solder reservoir recess. Therefore, the amount (thickness) of the fillet 15A formed to escape to the side wall in the width direction is reduced, and the possibility that a solder bridge is formed is reduced.

  Thus, the formation of the solder reservoir recess contributes to an increase in the total area of the side wall surface used for forming the solder fillet. The size and number of such solder reservoir recesses may be set in consideration of the size and thickness of the connection terminal portion.

  Incidentally, as shown in FIG. 11, when three rectangular solder reservoir recesses H3 are arranged in the length direction in the connection terminal portion T3, three solders formed along the wiring length direction of the connection terminal portion T3. A recess having the same depth as that of the solder reservoir recess H3 is shown as a virtual recess (shown by an alternate long and short dash line in FIG. 11 in the minimum region including both the contours of the solder reservoir recess H3 at both ends in the length direction of the reservoir recess H3. (Corresponding to (b)) When H, the total area of the inner side walls of the three solder reservoir recesses H3 as shown in FIG. 11 and FIG. It is preferable to set so that it may become large. In order to perform such setting, it is effective to appropriately adjust the intervals between the plurality of solder reservoir recesses.

(Modification of solder reservoir recess)
FIGS. 13-16 has shown the modification of the solder reservoir recessed part in the printed wiring board based on this Embodiment. In FIG. 13, a plurality of solder reservoir recesses 3B having a circular planar shape are intermittently arranged in the wiring length direction. FIG. 14 is a diagram in which a plurality of solder reservoir recesses 3C having an elliptical planar shape are intermittently arranged in the wiring length direction. In the modification shown in FIG. 14, the major axis of the ellipse is arranged so as to coincide with the wiring length direction, but it may be arranged so that the minor axis coincides with the wiring length direction. As shown in FIG. 3, the solder reservoir recess 3D may be arranged in a state where the elliptical long axis is inclined with respect to the wiring length direction. Further, in the solder reservoir recess 3E shown in FIG. 16, a plurality of rectangular annular solder reservoir recesses 3E are intermittently arranged in the wiring length direction. In addition, the planar shape of the solder reservoir recess may be a polygon other than a rectangle.

(Other examples)
Although the embodiment has been described above, it should not be understood that the description and the drawings, which constitute a part of the disclosure of the embodiment, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the above embodiment, the solder reservoir recess 7 is formed only in the connection terminal portion 3A of one printed wiring board 1 of the pair of printed wiring boards, but both connection terminals of the pair of printed wiring boards are used. You may form a solder reservoir recessed part in a part. In this case, the solder reservoir recesses may be formed at positions facing each other in a joined state, or may be formed at positions not facing each other.

  In the above embodiment, the case where both of the pair of printed wiring boards are flexible has been described. Of course, the present invention can be applied even if one of them is a rigid wiring board having no flexibility. Needless to say.

  Furthermore, in the said embodiment, although the connection area | region where the connection terminal part was arrange | positioned was provided in one surface of a printed wiring board, it is needless to say that a connection area | region may be provided in both surfaces (front and back) of a printed wiring board. .

It is a principal part top view of the printed wiring board which concerns on embodiment of this invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a principal part top view of the connection structure of the printed wiring board which concerns on embodiment of this invention. It is CC sectional drawing of FIG. It is DD sectional drawing of FIG. It is sectional drawing which shows the state which bent one printed wiring board in the connection structure of the printed wiring board which concerns on embodiment of this invention. (A) is a perspective view of a connection terminal portion showing a comparative example, (b) is a perspective view showing a connection terminal portion in which one solder reservoir recess is formed, and (c) is a connection terminal portion in which two solder reservoir recesses are formed. FIG. It is sectional drawing which shows the state which soldered the comparative example. It is sectional drawing which shows the state which soldered the connecting terminal part in which the solder reservoir recessed part was formed. It is a top view which shows the connecting terminal part in which the solder reservoir recessed part was formed. (A) is a perspective view of the connection terminal part of FIG. 11, (b) is a perspective view which shows the virtual recessed part shown with the dashed-dotted line of FIG. It is a top view which shows the modification of the solder reservoir recessed part of this Embodiment. It is a top view which shows the modification of the solder reservoir recessed part of this Embodiment. It is a top view which shows the modification of the solder reservoir recessed part of this Embodiment. It is a top view which shows the modification of the solder reservoir recessed part of this Embodiment. It is sectional drawing which shows the connection structure of the conventional printed wiring board. It is a top view which shows the connection structure of the other conventional printed wiring board. It is EE sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 10 Printed wiring board 2, 11 Insulating board 3, 12 Wiring 3A Connection terminal part 6 Connection area 7, 7A, 7B, 7C, 7D Solder reservoir recessed part 15 Solder 15A Fillet

Claims (10)

At least one surface of the insulating base material has a connection region in which connection terminals of a plurality of wirings are arranged at intervals,
The connection terminal portion is recessed from the soldering planned surface of the connection terminal portion toward the insulating base material along the wiring length direction, and the planar shape of the soldering planned surface is surrounded by a closed curve. A printed wiring board having a solder reservoir recess having a contour.   The printed wiring board, wherein the connection terminal portion includes a plurality of solder reservoir recesses formed intermittently along a wiring length direction.   The printed wiring board according to claim 1, wherein a solder plating layer is formed on a surface to be soldered of the connection terminal portion.   4. The printed wiring board according to claim 1, wherein the planar shape of the solder reservoir recess is selected from a polygon, a circle, and an ellipse. 5. The solder reservoir is a minimum region including both the outlines of the two solder reservoir recesses located at both ends in the length direction among the plurality of solder reservoir recesses formed along the wiring length direction of the connection terminal portion. When a recess having the same depth as the recess is a virtual recess,
5. The printed wiring board according to claim 2, wherein a total area of inner walls of the plurality of solder reservoir recesses is larger than a total area of inner walls of the virtual recesses. . A connection structure in which a plurality of wiring connection terminal portions are arranged at intervals on a pair of printed wiring boards, and the connection terminal portions that are joined together in the pair of printed wiring boards are soldered together,
Of the pair of printed wiring boards, one of the connection terminal portions is recessed along the wiring length direction from the soldering surface of the connection terminal portion toward the insulating base material, and is scheduled to be soldered A solder reservoir recess having a contour in which the planar shape of the surface is surrounded by a closed curve is formed,
The connection of printed wiring boards, wherein the connection terminal portions to be joined together have solder accumulated along the inner wall of the solder reservoir recess, and a fillet is formed on the outer wall of the connection terminal portions. Construction.   The printed wiring board connection structure according to claim 6, wherein a plurality of the solder reservoir recesses are formed along a length direction of the connection terminal portion.   8. The printed wiring board connection structure according to claim 6, wherein at least one of the pair of printed wiring boards has flexibility.   The printed wiring board connection structure according to any one of claims 6 to 8, wherein a planar shape of the solder reservoir recess is selected from a polygonal shape, a circular shape, and an elliptical shape. Among the plurality of solder reservoir recesses formed along the wiring length direction of the connection terminal portion, the solder reservoir recess and the depth are the smallest areas including the outlines of the two solder reservoir recesses at both ends in the length direction. When the concave portion having the same height is a virtual concave portion,
10. The printed wiring board according to claim 7, wherein a total area of inner walls of the plurality of solder reservoir recesses is larger than a total area of inner walls of the virtual recesses. Connection structure.

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