JPH06164120A - Printed wiring board - Google Patents

Abstract

PURPOSE:To attach a cubic structure easily wettable with solder to a conductive sub-land when soldering a surface mount component attached to a printed circuit board by using flow solder. CONSTITUTION:At the rear surface 1b side of a printed wiring board 1, a plurality of terminals 13 of a surface mount component 12 are pre-positioned and pre-mounted to a plurality of copper foil lands 2; and a cubic structure 4, which is easily wetted with molten solder 22 is attached in advance to a conductive sub-land 3 which is adhered with a film to a portion near the rear side of the copper foil land 2 for soldering a rear terminal 13 in the board advancing direction of the surface mount component 12. And an excess amount of molten solder 22 adhered to the terminal 13 at the rear in the board advancing direction of the surface mount component 12 is absorbed to the cubic structure 4 when soldering the surface mount component while moving the printed wiring board 1 pre-mounted with the surface mount component 12 and a cubic structure 4 through flow solder 20 in a predetermined advancing direction of the board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a three-dimensional structure in which a conductive waste land is easily wetted by solder when a surface mount component mounted on a printed wiring board is soldered using a flow solder to prevent a solder short circuit. The present invention relates to an attached printed wiring board.

[0002]

2. Description of the Related Art With the miniaturization of electronic equipment, miniaturization of printed wiring boards in electronic equipment is also required. Therefore, it is well known that surface mount components are frequently used to mount electronic components on a printed wiring board with high density. Generally, the surface mount components (Surface M)
The mounted device or SMD) is made by integrating electronic components such as resistors, capacitors, diodes, transistors, filters, and transformers into an ultra-small rectangular shape (square shape, rectangular shape). In addition, the plurality of terminals for soldering, which are integrally formed so as to project from the surface-mounted component, are formed with a very small interval between adjacent terminals. These terminals are soldered to a plurality of conductive lands (hereinafter referred to as copper foil lands) pre-coated on the printed wiring board. Since the surface on which the plurality of terminals are soldered is the same surface, it is called a surface mount component.

Here, the soldering of the surface-mounted component mounted on the conventional printed wiring board will be described with reference to FIGS. 4 to 8. FIG. 4 is a side view for explaining the soldering of the surface mount component mounted on the conventional printed wiring board using the flow solder, and FIG. 5 is the side view for soldering the surface mount component mounted on the conventional printed wiring board. A perspective view showing the back side of a printed wiring board coated with conductive lands so as to prevent a solder short circuit, and FIG. 6 shows a solder short circuit when soldering a surface-mounted component mounted on a conventional printed wiring board. Is a perspective view of the printed wiring board with a conductive waste land attached to the back surface of the printed wiring board. FIGS. 7 and 8 show the shapes of the surface mount components and various conductive properties corresponding to the protruding direction of the terminals of the surface mount components. It is a top view showing the shape of a waste land. In FIG. 4, electronic parts 10 such as resistors, capacitors, diodes, transistors, filters, and transformers have respective terminals 11 on the upper surface 1a side of the conventional printed wiring board 1A and holes (not shown) in the printed wiring board 1A. A copper foil land (not shown) with a film on the back surface 1b side
It is installed so as to protrude. On the other hand, printed wiring board 1
On the back surface 1b side of A, a plurality of terminals 13 of the surface mount component 12 described above are preliminarily positioned and mounted on a plurality of copper foil lands (not shown) using an adhesive or the like.

Then, the conventional printed wiring board 1A on which the electronic component 10 and the surface mount component 12 are mounted as described above.
When the printed wiring board 1A is moved in a predetermined board advancing direction (arrow direction) while the back surface 1b side of the above is opposed to the solder jet port 21 of the flow solder 20, the molten solder 22 jetted from the solder jet port 21 becomes an electronic component. The terminals 11 and 10 of the surface mount component 12 and the copper foil lands (not shown) of the printed wiring board 1A are contacted and soldered.
At this time, the board traveling direction of the printed wiring board 1 A is obliquely upward with respect to the R-shaped surface of the molten solder 22 while the back surface 1 b is in contact with the R-shaped surface of the molten solder 22 ejected from the solder jet port 21. It is progressing while tilting about 5 degrees. At this time, since the printed wiring board 1A is inclined obliquely upward, an excessive amount of the molten solder 22 attached to the back surface 1b of the printed wiring board 1A can drop by gravity onto the molten solder 22 in the lower flow solder 20. Has become. Further, the temperature of the molten solder 22 is maintained around 250 ° C. However, since the package of the surface mount component 12 uses a heat resistant resin material or the like, no trouble occurs in the elements inside the package. Although not described in detail here, as another method of soldering the surface mount component, a certain amount of well-known cream solder is applied to a plurality of copper foil lands of a printed wiring board, and the surface mount component is mounted on the cream solder. Position and place multiple terminals in correspondence with multiple copper foil lands on the printed wiring board, then pass the printed wiring board on which surface-mounted components are placed through a well-known reflow oven to melt the cream solder in the reflow oven. Then, there is also a method of soldering the surface mount component.

[0005]

By the way, as shown in FIG. 4, when the electronic component 10 and the surface mount component 12 mounted on the conventional printed wiring board 1A are soldered by using the flow solder 20, The electronic component 10 mounted on the upper surface 1a side and the surface mount component 12 mounted on the rear surface 1b side
6 can be simultaneously soldered, but in particular, among the plurality of terminals 13 of the surface mount component 12 mounted on the back surface 1b side of the printed wiring board 1A, the solder as shown in FIG. A short circuit (also called a solder bridge) is likely to occur. The reason why a solder short circuit is likely to occur between the terminals 13 on the rear side of the surface mounting component 12 in the board traveling direction is that the printed wiring board 1A moves in a predetermined board traveling direction (arrow direction) as shown in FIG. At this time, among the terminals 13 of the surface mount component 12, the terminals 13 on the front side (the right side in the drawing) of the board traveling direction are sequentially soldered to the copper foil lands (not shown) of the printed wiring board 1A, and the printed wiring Although the excess amount of the molten solder 22 adhering to the terminal 13 on the front side in the board traveling direction flows toward the terminal 13 side on the rear side (left side in the drawing) in the board traveling direction by tilting and moving the board 1A diagonally, As the wiring board 1A moves away from the molten solder 22 in the flow solder 20,
An excessive amount of the molten solder 22 attached to the terminals 13 on the rear side of the board traveling direction is attached between the terminals 13 with a narrow interval and gradually hardens to form a fillet (a lump of solder in a mountain shape), that is, to stand alone. Terminal 13 at the rear of the power board traveling direction
It is not uncommon for solder shorts to occur here because they remain in the gap.

Therefore, as shown in FIG.
Japanese Patent No. 7183 discloses a square surface mount component 12
A plurality of copper foil lands 2 corresponding to the plurality of terminals 13 of the surface mount component 12A are film-coated on the back surface 1b of the conventional printed wiring board 1A on which (12A) is mounted, and the plurality of copper foil lands are also provided. 2 of the two copper foil lands 2a and 2b adjacent to each other on two orthogonal sides, the corners 2a ₁ and 2b facing _{each other} .
Corner 2a ₁ and corner 2b by cutting ₁ diagonally
Although there is a technical idea that the interval of ₁ is widened to reduce the solder short circuit generated between the terminals 13 at the rear of the board traveling direction, a large amount of the excessive amount of the molten solder 22 adheres between the terminals 13 at the rear of the board traveling direction. If this happens, the solder short circuit cannot be completely eliminated.

Further, as another method for preventing the occurrence of the solder short circuit, as shown in FIG.
A copper foil land 2 for soldering the terminal 13 of the surface-mounted component 12 is formed on the back surface 1b side of A, and the terminal 1 at the rear of the printed wiring board 1A with respect to the board traveling direction.
In the vicinity of the rear of the copper foil land 2 to which 3 is soldered, a conductive waste land 3 is preliminarily attached with a film. This conductive land 3
Does not solder the terminals 13 of the surface-mounted component 12, but has a function of attracting an excessive amount of the molten solder 22 attached to the terminals 13 on the rear side of the board traveling direction. It prevents solder short circuit.

At this time, the square surface mount component 12A shown in FIGS. 7 (A) to (F) and FIGS. 8 (A) to 8 (E).
Like the rectangular surface mount component 12B shown in FIG. 2, the shape of the conductive waste land 3 is formed in various shapes depending on the protruding direction of the terminal 13 protruding from the surface mount components 12A and 12B. However, no matter how the shape of the conductive waste land 3 is changed as shown in FIGS. 7 and 8, the terminal 13 on the rear side in the substrate advancing direction as shown in FIG. 6 is obtained.
We cannot completely eliminate the solder short circuit that occurs between
When the flow solder 20 is used, it is difficult to solder the surface mount component 12 mounted on the conventional printed wiring board 1A without causing a solder short circuit. Therefore, when the surface mount component 12 is soldered, When a solder short circuit occurs between the terminals 13 at the rear of the board traveling direction, it takes time to repair the solder short circuit by a manual process in a later step.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the first invention is to project from one surface mount component on one surface side facing the solder jet opening of the flow solder. In a printed wiring board in which conductive lands for soldering the plurality of terminals are film-formed corresponding to the plurality of terminals, and the plurality of terminals are pre-positioned and mounted on the plurality of conductive lands. , One surface side of the printed wiring board is moved in a predetermined board advancing direction while being in contact with molten solder jetted from the solder jet port, and a plurality of terminals of the surface mount component are soldered to the plurality of conductive lands. At the time of attachment, a conductive waste land is filmed in the vicinity of the rear of the conductive land for soldering the terminal behind the predetermined board traveling direction, and the melting half is applied to the conductive waste land. A printed wiring board, characterized in that fitted with wet easily three-dimensional structure in advance to.

A second invention is the printed wiring board according to the first invention, wherein the height of the three-dimensional structure is substantially equal to the height of the terminals of the surface mount component, or the surface mount component. The printed wiring board is characterized in that the height is set to be higher than the height of the terminals and not to exceed the height of the surface mount component.

Furthermore, a third aspect of the present invention is, in the printed wiring board according to the first and second aspects, for sucking an excessive amount of the molten solder attached to the terminal at the rear of the board traveling direction in the three-dimensional structure. The printed wiring board is characterized in that a hollow portion is formed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the printed wiring board according to the present invention will be described in detail below with reference to FIGS.
For convenience of explanation, the same reference numerals will be given to the same constituent members as the constituent members shown above, and the constituent members shown previously will be appropriately described as necessary, and different from the conventional structure. The members will be described with new reference numerals.

FIG. 1 is a rear perspective view showing a state in which a surface mounting component and a three-dimensional structure are preliminarily mounted on a printed wiring board according to the present invention and the surface mounting component is soldered, and FIG. FIG. 3 is a side view for explaining the soldering of the surface mount component mounted on the printed wiring board according to the present invention, and FIG. 3 is a perspective view showing the printed wiring board according to the present invention on which the three-dimensional structure of the modification is mounted from the back side. Is.

As shown in FIG. 1, the printed wiring board 1
On the back surface (one surface) 1b side, a plurality of conductive lands (hereinafter referred to as copper foil lands) 2 having a plurality of terminals 13 integrally protruding from the surface mount component 12 attached to the back surface 1b side are formed. Correspondingly, it is preliminarily positioned and attached using an adhesive material or the like. The surface mount component 12 has
For example, a square surface mount component 12A, a rectangular surface mount component 12B, etc. are mounted. The back surface 1b side of the printed wiring board 1 on which the surface mount components 12 (12A, 12B) are mounted is a surface side facing the solder jet port 21 of the flow solder 20. At this time, as shown in FIG. 2, the back surface 1b of the printed wiring board 1 is in contact with the R-shaped surface of the molten solder 22 jetted from the solder jet port 21 in the same direction as in the conventional case. And about 5 degrees diagonally above the R-shaped surface of the molten solder 22.
It is moved while tilting about a degree. Therefore, the plurality of terminals 13 protruding from the solder surface mount component 12 (12A, 12B) are provided by the plurality of conductive lands 2 (hereinafter referred to as copper) formed on the printed wiring board 1 by the molten solder 22 jetted from the solder jet port 21. The soldering to the foil land 2) is the same as the conventional one.

Here, among the surface mount components 12,
In the case of the square surface mount component 12A, the plurality of terminals 1 are provided from the four side surfaces 12b to 12e of the surface mount component 12A.
3 are integrally projected, and a plurality of copper foil lands 2 are formed on the back surface 1b side of the printed wiring board 1 corresponding to the plurality of terminals 13. Then, the surface mount component 12A with respect to the predetermined traveling direction of the printed wiring board 1
Of the plurality of terminals 13 of the surface-mounted component 12A among the plurality of terminals 13 of the surface-mounted component 12A. Solder 22 is the terminal 1 at the rear of the board traveling direction
It is arranged so as to flow sequentially to the 3 side.

Further, the corner portion 12 of the surface mount component 12A
In the vicinity of “a” and in the vicinity of the rear of the terminal 13 on the rear side in the direction of travel of the substrate, a conductive waste land 3 is formed as in the conventional example. That is, the conductive waste land 3 is disposed in the predetermined board traveling direction (arrow direction) of the printed wiring board 1.
A film is formed behind the intersection of the side surface 12b and the side surface 12e of the surface mount component 12A. In other words, with respect to the predetermined board traveling direction (arrow direction) of the printed wiring board 1,
The terminal 13 projecting from the side surface 12b and behind the board traveling direction and the terminal 13 projecting from the side surface 12e behind the board moving direction.
A conductive waste land 3 is provided in the vicinity of the rear of the conductive land 2 for soldering. Of course, the conductive land 3
Is arranged at a position where an excessive amount of the molten solder 22 attached to the terminal 13 on the rear side of the surface mounting component 12A in the board traveling direction can flow into the conductive waste land 3.

On the other hand, in the case of the rectangular surface mount component 12B, the long side surfaces 12g and 12i of the surface mount component 12B are used.
A plurality of terminals 13 are integrally projected from the plurality of terminals, and a plurality of copper foil lands 2 are film-formed corresponding to the plurality of terminals 13 as described above. The short side surface 12f of the surface-mounted component 12B is arranged so as to match the predetermined substrate traveling direction with respect to the predetermined substrate traveling direction of the printed wiring board 1. Here, a plurality of surface-mounted components 12B are also arranged. Terminal 13
Among them, the excessive amount of the molten solder 22 attached to the terminal 13 on the front side in the board traveling direction is arranged so as to sequentially flow to the terminal 13 side on the rear side in the board traveling direction. Further, with respect to a predetermined board traveling direction (arrow direction) of the printed wiring board 1, the rear of the conductive land 2 for soldering the terminal 13 behind the board traveling direction protruding from the long side surfaces 12g and 12i of the surface mount component 12B. In the vicinity, conductive waste lands 3 and 3 are formed so as to face each other. Again, the conductive waste land 3,
The arrangement position of 3 is set to a position where an excessive amount of the molten solder 22 attached to the terminal 13 behind the surface mounting component 12B in the board traveling direction can flow into the conductive waste lands 3, 3.

Here, the main point of the present invention is that the conductive waste land 3 is preliminarily attached to the above-mentioned position on the back surface 1b side of the printed wiring board 1 by a film, and the conductive waste land 3 is further provided. That is, the three-dimensional structure 4 is attached in advance so that the molten solder 22 is easily wetted and the excess amount of the molten solder 22 attached to the terminal 13 on the rear side of the board traveling direction can be blown.

That is, as shown in FIG. 1 and FIG. 2, the surface mount component 12 (12
A, 12B) terminals 13 are preliminarily positioned and mounted on the copper foil lands 2, and the three-dimensional structure 4 is preliminarily mounted on the conductive waste land 3. The three-dimensional structure 4 may be, for example, a lump of copper or the like, or may be a nominal 2125 type surface mount component having a length of 2 mm and a width of 1.25 mm, or a length of 3.2 mm and a width of 1. It may be a surface mount component having a nominal size of 3216 and having a size of 6 mm, and may be in any form as long as it is a three-dimensional structure that is easily wet by the molten solder 22. Further, a plurality of three-dimensional structures 4 may be attached to the conductive waste land 3.

Here, the surface mount component 12 (12A, 12B) and the three-dimensional structure 4 are provided on the back surface 1b of the printed wiring board 1.
After attaching each of them, the back surface 1b of the printed wiring board 1 is in contact with the R-shaped surface of the molten solder 22 in the flow solder 20, and about 5 degrees obliquely upward with respect to the R-shaped surface of the molten solder 22. When the terminals 13 are moved while being tilted to some extent, the terminals 13 among the plurality of terminals 13 of the surface mount component 12 are transferred to the copper foil lands 2 by the molten solder 22 in the order of the terminal 13 in the board traveling direction to the terminal 13 in the board traveling direction. While being soldered, the printed wiring board 1 is inclined obliquely upward, and an excessive amount of the molten solder 22 attached to the terminals 13 ahead of the board traveling direction sequentially flows toward the terminal 13 side behind the board traveling direction due to gravity. Furthermore, the terminal 13 on the rear side of the board traveling direction
An excessive amount of the molten solder 22 attached to is blown to the three-dimensional structure 4 by the surface tension and gravity of the solder itself. Therefore, since the excess amount of the molten solder 22 does not adhere to the terminal 13 on the rear side in the board traveling direction among the plurality of terminals 13 of the surface-mounted component 12, the excess amount of the molten solder 22 is applied between the terminals 13 having a narrow interval. Solder short circuit does not occur because it does not adhere. At this time, as the printed wiring board 1 moves, the excess amount of the molten solder 22 attached to the terminal 13 on the front side in the board traveling direction flows to the terminal 13 side on the rear side in the board traveling direction as described above. Since an excessive amount of molten solder 22 does not adhere to the terminal 13 on the other side in the direction, a solder short circuit does not occur. Then, part of the molten solder 22 blown to the three-dimensional structure 4 drops to the molten solder 22 in the lower flow solder 20 due to gravity, while the remaining molten solder 22 adheres to the three-dimensional structure 4. Will remain.

Further, as shown in FIG. 2, the three-dimensional structure 4
Height H of the surface mount component 12 is substantially equal to the height h ₁ of the terminal 13 of the surface mount component 12, or higher than the height h ₁ of the terminal 13 of the surface mount component 12 and the height h _{2 of the} surface mount component 12. By setting the height so as not to exceed, the excess amount of the molten solder 22 attached to the terminal 13 at the rear of the board traveling direction is attracted to the three-dimensional structure 4 by the surface tension of the solder itself, and is lowered by gravity. While being dropped onto the three-dimensional structure 4, the three-dimensional structure 4 having the above-mentioned height H is surely blown to the three-dimensional structure 4, and if the height H of the three-dimensional structure 4 is within the above-specified range, a large amount of molten solder is applied to the three-dimensional structure 4. Since 22 is not attached, there is an advantage that a solder short circuit does not occur at all between the terminals 13 on the rear side in the board traveling direction.

In the printed wiring board 1 according to the present invention having the above-described structure, the printed wiring board 1 on which the surface mount component 12 and the three-dimensional structure 4 are mounted in advance is used as the flow solder 20.
The molten solder 22 is moved while moving in a predetermined substrate traveling direction.
When the surface mount component 12 is soldered by the above, an excessive amount of the molten solder 22 attached to the terminal 13 of the plurality of terminals 13 of the surface mount component 12 on the rear side in the board traveling direction is attracted to the three-dimensional structure 4. Terminal 13 behind the board traveling direction
No solder short circuit occurs between them, that is, the plurality of terminals 13 of the surface mount component 12 are independent of each other.
Since it is surely soldered to each copper foil land 2 corresponding to, the quality and reliability of the printed wiring board 1 to which the surface mount component 12 is soldered are remarkably improved. Along with this, there is no need to repair a solder short circuit in a later step as in the conventional case, and the soldering work of the printed wiring board 1 on which the surface mount component 12 is mounted is significantly improved. Further, there is an advantage that the reliability of an electronic device (not shown) using the printed wiring board 1 in which the three-dimensional structure 4 which easily wets the molten solder 22 is attached is improved.

Next, as shown in FIG. 3, as a modified example of the three-dimensional structure 4 which is easily wet with the molten solder 22, a metallic test point having a hollow portion 4a formed by bending a hollow inside using a sheet metal member, for example. Alternatively, a metallic test point having a hollow portion 4b whose inside is formed into a hollow cylinder may be applied. The hollow portion 4a (or 4b) formed in the three-dimensional structure 4 has an extra amount of the molten solder 2 attached to the terminal 13 on the rear side of the surface mounting component 12 in the board traveling direction.
It is formed hollow so that 2 can be sucked in reliably. The three-dimensional structure 4 having the hollow portion 4a (or 4b) may be a commercially available test point for checking the operation of the printed wiring board 1. Further, the height H of the three-dimensional structure 4 of this modified example
In the same manner as described above, the height h of the terminal 13 of the surface mount component 12
The height is set to be substantially equal to ₁ or higher than the height h ₁ of the terminal 13 of the surface mount component 12 and not higher than the height h ₂ of the surface mount component 12. Therefore, the printed wiring board 1 on which the three-dimensional structure 4 with the surface mount component 12 and the hollow portion 4a (or 4b) is mounted is attached to the flow solder 20.
Molten solder 2 while moving in a predetermined substrate traveling direction inside
When the surface mount component 12 is soldered by means of 2, the excess amount of the molten solder 22 adhering to the terminal 13 on the rear side of the surface mount component 12 in the direction of travel of the substrate is partially covered by the hollow portion 4a of the three-dimensional structure 4.
(Or 4b) is surely sucked, the remaining part falls to the molten solder 22 in the flow solder 20, and the remaining part remains attached to the periphery of the three-dimensional structure 4. It is possible to more reliably prevent a solder short circuit that occurs between the terminals 13.

[0024]

According to the printed wiring board of the present invention described in detail above, in the first aspect, a plurality of conductive lands for soldering a plurality of terminals of the surface mount component mounted on the printed wiring board. Among them, a conductive waste land is formed in the vicinity of the rear of the conductive land for soldering the terminal at the rear with respect to the board traveling direction, and a three-dimensional structure easily attached to the molten solder is attached to the conductive waste land. Therefore, when soldering the surface mount component while moving the printed wiring board on which the surface mount component and the three-dimensional structure are preliminarily mounted in the flow solder in the predetermined board traveling direction, among the plurality of terminals of the surface mount component, Excessive amount of molten solder adhering to the terminals on the rear side of the board traveling direction is attracted to the three-dimensional structure, so that no solder short circuit will occur between the terminals on the rear side of the board traveling direction. That is, since the plurality of terminals of the surface mount component are independently and reliably soldered to the respective conductive lands corresponding to the respective terminals, the quality and reliability of the printed wiring board to which the surface mount component is soldered is remarkably high. improves. Further, along with this, there is no need to repair a solder short circuit in a later step as in the conventional case, and the soldering work of a printed wiring board on which surface mount components are mounted is significantly improved. Further, there is an advantage that the reliability of an electronic device using a printed wiring board having a three-dimensional structure easily wetted by the molten solder is improved.

Further, in the present invention, the height of the three-dimensional structure is substantially equal to the height of the terminals of the surface mount component, or higher than the height of the terminals of the surface mount component and the height of the surface mount component. By setting the height so as not to exceed the height, the effect according to claim 1 can be obtained, and in particular,
Excessive amount of molten solder adhering to the terminal at the rear of the board traveling direction is attracted to the three-dimensional structure by the surface tension of the solder itself and is surely attached to the three-dimensional structure of the height set above while falling downward due to gravity. In this case, since a large amount of molten solder does not adhere to the three-dimensional structure within the height range of the three-dimensional structure set above, there is an advantage that a solder short circuit does not occur between terminals at the rear of the board traveling direction. is there.

Further, in the third aspect of the present invention, the three-dimensional structure has a hollow portion for sucking an excessive amount of the molten solder attached to the terminal at the rear of the board traveling direction.
In addition to the effect of claim 2, especially, since a part of the excessive amount of the molten solder attached to the terminal at the rear of the board traveling direction is surely sucked into the hollow portion of the three-dimensional structure, the terminal of the surface mount component is It is possible to more reliably prevent a solder short circuit that occurs between the two.

[Brief description of drawings]

FIG. 1 is a rear perspective view showing a state in which a surface mounting component and a three-dimensional structure are mounted in advance on a printed wiring board according to the present invention and the surface mounting component is soldered.

FIG. 2 is a side view for explaining the soldering of the surface mount component mounted on the printed wiring board according to the present invention using the flow solder.

FIG. 3 is a perspective view showing a printed wiring board according to the present invention, on which a three-dimensional structure of a modified example is mounted, from the back surface side.

FIG. 4 is a side view for explaining soldering of surface mount components mounted on a conventional printed wiring board using a flow solder.

FIG. 5 is a perspective view showing a back side of a printed wiring board on which conductive lands are formed so as to prevent a solder short circuit when soldering a surface-mounted component mounted on a conventional printed wiring board.

FIG. 6 is a perspective view showing a back side of a printed wiring board having a film of conductive waste lands for preventing a solder short circuit when soldering a surface-mounted component mounted on a conventional printed wiring board.

FIG. 7 is a plan view showing the shapes of the surface-mounted components and various conductive waste land shapes corresponding to the protruding directions of the terminals of the surface-mounted components.

FIG. 8 is a plan view showing the shapes of surface mount components and the shapes of various waste runs corresponding to the protruding direction of the terminals of the surface mount components.

[Explanation of symbols]

1 ... Printed wiring board, 1b ... One surface (back surface), 2 ...
Conductive land (copper foil land), 3 conductive waste land,
4 ... Three-dimensional structure, 4a, 4b ... Hollow part, 12 (12A,
12B) ... Surface mount component, 13 ... Surface mount component terminal,
20 ... flow solder, 21 ... solder jet flow port, 22 ... molten solder, H ... three-dimensional structure of the height, h 1 _... surface mount components of the terminal height, h 2 _... surface mounting component height.

Claims (3)

[Claims] 1. A conductive land for soldering a plurality of terminals projecting from one surface-mounted component on one surface facing a solder jet port of a flow solder, with a film corresponding to the plurality of terminals. And, in the printed wiring board in which the plurality of terminals are pre-positioned and mounted on the plurality of conductive lands, one surface side of the printed wiring board is brought into contact with the molten solder ejected from the solder jet port. When the plurality of terminals of the surface mount component are moved to a predetermined board traveling direction and soldered to the plurality of conductive lands, the conductiveness for soldering the terminals rearward with respect to the predetermined board traveling direction Conductive abandoned land is filmed near the rear of the land, and
A printed wiring board, wherein a three-dimensional structure easily wetted by the molten solder is attached to the conductive waste land in advance. 2. The printed wiring board according to claim 1, wherein the height of the three-dimensional structure is substantially equal to the height of the terminals of the surface mount component or higher than the height of the terminals of the surface mount component. Moreover, a printed wiring board is set to a height not exceeding the height of the surface mount component. 3. The printed wiring board according to claim 1, wherein the three-dimensional structure is provided with a hollow portion for sucking an excessive amount of the molten solder attached to the terminal at the rear of the board traveling direction. A printed wiring board characterized in that