JP2004079776A - Method for mounting printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for mounting a printed wiring board which can effectively make a large current flow between printed wiring boards, and can lower component costs, thereby enabling to be thinned and saving a space thereof. <P>SOLUTION: In a method for mounting a sub-printed wiring board 11 on the surface of a main printed wiring board 10, this mounting method comprises steps of temporarily fixing a holding projection 20 of a conductive connection pin 18 to a pin holding hole 22 of the sub-printed wiring board 11, printing cream solder 25 to the insertion position of the holding projection 20 and a solder connection pad mounted by an L-shaped connection end 21 at the other end of the connection pin 18, mounting the connection end 21 of the connection pin 18 to the connection pad of the main printed wiring board 10, and melting the cream solder 25 so that the holding projection 20 is connected to the sub-printed wiring board 11 and the connection end 21 is connected to the main printed wiring board 10 by surface mounting. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of mounting a printed wiring board on which a part of a circuit is formed as a sub-printed wiring board and surface-mounted on a main printed wiring board. The present invention relates to a method for mounting a printed wiring board, which is used when surface mounting is performed on a main printed wiring board.
[0002]
[Prior art]
Generally, a method of configuring an electronic circuit in which a surface mounting component is mounted on a printed wiring board is assembled by the following steps.
First step: The solder screen is brought into close contact with the printed wiring board, and cream solder is screen-printed on the electrode portion of the printed wiring board through the hole of the solder screen.
Second step: The electronic component is mounted on the printed wiring board with a chip mounter or the like so that the printed cream solder and the electrode portion of the electronic component match.
Third step: melting the cream solder in a high-temperature furnace such as a reflow furnace, and electrically and mechanically connecting the terminals of the electronic components and the pads of the printed wiring board to form an electronic circuit.
[0003]
Conventionally, there has been a method shown in FIG. 9 or a method shown in FIG. 10 for forming a part of a circuit into a sub-printed wiring board and surface mounting it on a main printed wiring board.
In the method shown in FIG. 9, when the electronic components 12 are surface-mounted on the main printed wiring board 10 and the sub-printed wiring board 11, respectively, both the main printed wiring board 10 and the sub-printed wiring board 11, The main printed wiring board side connector 13 and the sub printed wiring board side connector 14 are mounted by surface mounting or through hole mounting. Then, the sub-printed wiring board 11 is surface-mounted on the main printed wiring board 10 by connecting the main printed wiring board side connector 13 and the sub-printed wiring board side connector 14 to each other.
[0004]
In the method shown in FIG. 10, a plurality of L-shaped pins 16 are mechanically driven into a long and thin insulator 15 at predetermined intervals, and the pins 16 connected by the insulator 15 are temporarily fixed with a jig or the like, A straight end protruding from the insulator 15 is passed through a hole formed in the sub-printed wiring board 11, and the protruding end at the upper end is fixed to the sub-printed wiring board 11 using a soldering iron or a dip with solder 17. The lower end of the L-shape is connected to the main printed wiring board 10 using solder 17.
[0005]
[Problems to be solved by the invention]
The conventional method as described above has the following problems.
(1) When a large current of 40 A or more is supplied to the high-speed CPU in the DC-DC converter having the sub printed wiring board 11, the main printed wiring board side connector 13 and the sub printed wiring board side connector 14 are interposed. In power supply, the loss due to the contact resistance of the connector is large and cannot be ignored. For example, assuming that the current is 40 A and the contact resistance is 8 mΩ, a voltage drop of 40 A × 8 mΩ = 320 mV is generated, and the accuracy of the voltage variable step required by the CPU deteriorates.
(2) High-speed CPUs generate enormous amounts of heat, but portable electronic devices such as notebook personal computers are required to satisfy air permeability for heat dissipation and to be light and thin. Cannot meet these demands.
[0006]
(3) To connect the pins 16 for connecting the sub-printed wiring board 11 to the main printed-wiring board 10 to the sub-printed wiring board 11 by using a soldering iron or a dip by hand, a lot of man-hours are required. In other words, the mounting positions of the sub printed wiring board 11 and the main printed wiring board 10 vary.
(4) Normally, the main printed wiring board 10 has a larger area than the sub-printed wiring board 11, so if the electronic components 12 that generate heat are mounted on the main printed wiring board 10, Blocks the flow of air and becomes an obstacle to heat dissipation.
(5) As shown in FIG. 9, elongated main printed wiring board-side connectors 13 and sub-printed wiring board-side connectors 14 are mounted on the main printed wiring board 10 and the sub-printed wiring board 11, respectively. The method of mounting by hole mounting complicates the structure of the multiple connectors 13 and 14 and increases the cost.
[0007]
The present invention has been made in order to solve these problems, and a large current can efficiently flow between printed wiring boards, thereby reducing the cost of parts, reducing the thickness, and saving space. It is an object of the present invention to provide a method for mounting a wiring board.
[0008]
[Means for Solving the Problems]
The present invention provides a method for mounting a printed wiring board on which a sub-printed wiring board 11 on which an electronic component 12 is mounted is surface-mounted on a main printed wiring board 10. A step of inserting the portion 20 into the pin locking hole 22 of the sub-printed wiring board 11 and temporarily fixing the same; an insertion position of the locking projection 20 in the sub-printed wiring board 11; Printing cream solder 25 on the solder connection pads of the main printed wiring board 10 on which the connection end portions 21 are bent, and connecting the connection end portions 21 of the connection pins 18 to the connection pads of the main printed wiring board 10. Mounting step, dissolving the cream solder 25, fixing the locking projection 20 of the connection pin 18 to the sub-printed wiring board 11, and connecting the connection end 21 of the connection pin 18 to the main board. A mounting method of the printed wiring board, characterized in that comprising the step of surface mounting connection to the cement wiring board 10.
[0009]
Adopting such a mounting method has the following excellent effects.
(1) Since a contact resistance can be reduced, a large current can flow between printed wiring boards.
(2) Since no connector is used, the cost of parts can be reduced.
(3) Surface mounting on the main printed wiring board eliminates the need for through-hole holes, which is extremely advantageous for wiring of a multilayer printed wiring board.
(4) By providing positioning pins in addition to the connection pins, the mounting accuracy is improved in a simple process.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
A: First, the assembly of the sub printed wiring board 11 will be described.
First step: connection pins 18 are prepared. As shown in FIGS. 1 and 2, a plurality of pin locking holes 22 into which the connection pins 18 are inserted and fixed are formed in the sub-printed wiring board 11 as required for wiring.
Positioning pins 19 are prepared as needed. Pin locking holes 22 are formed in the sub-printed wiring board 11 at several places such as both end portions for the positioning pins 19.
[0011]
As shown in FIG. 3, the connection pin 18 is formed by bending a good conductive metal wire into an L-shape. One end of the connection pin 18 is formed from all sides as shown in (a-1) and (a-2). A locking projection 20 called a star, which is crushed and swells outward at 90-degree intervals and slightly swells outward, is formed, and the tip is formed in a sharpened state to facilitate insertion. Further, as shown in (a-3), the other end is bent by 90 degrees so that the flat portion of the square section becomes the bottom surface, and becomes the connection end 21 with the main printed wiring board 10. I have.
The inner diameter of the pin locking holes 22 formed at predetermined intervals near both ends of the sub-printed wiring board 11 is formed slightly smaller than the diagonal length of the locking projection 20, and the connection pin 18 is press-fitted. It has become so.
[0012]
As shown in FIG. 1, the positioning pin 19 is made of the same metal wire as the connection pin 18, and an upper end portion is formed with a locking projection 20 similar to the connection pin 18. It is straight, and the length is slightly longer than the connection end 21 of the connection pin 18. Further, a positioning hole 23 for smoothly inserting the positioning pin 19 is formed at a predetermined position of the main printed wiring board 10.
[0013]
The connection pin 18 is not limited to a metal wire having a square cross section, but a metal wire having a circular cross section, (c-1) and (c-3) as shown in (b-1) and (b-3). May be a metal wire having a rectangular cross section, or a metal wire having an elliptical cross section as shown in (d-1) and (d-3). The same applies to the positioning pins 19.
[0014]
Second step: The locking projection 20 of the connection pin 18 is driven into the pin locking hole 22 of the sub-printed wiring board 11 as shown in FIG. The tip of the inserted connection pin 18 is set to protrude from the upper surface of the sub-printed wiring board 11 by a small dimension h.
The direction of the connection end portion 21 of the connection pin 18 when driven is determined by the direction and shape of the pattern of the connection pad formed on the main printed wiring board 10, but is usually as shown in FIGS. To the outside. The fitting portion of the locking projection 20 with the pin locking hole 22 is more securely fixed by the bulging portion protruding in four directions, and is sufficient as temporary fixing until soldering in the next step. .
Similarly, the required number of connection pins 18 are driven into the pin locking holes 22 of the sub-printed wiring board 11 and temporarily fixed.
[0015]
In addition to the connection pins 18, the locking projections 20 of the positioning pins 19 are driven into the pin locking holes 22 of the sub-printed wiring board 11 and temporarily fixed as necessary. In the example of FIG. 2, positioning pins 19 are fixed at two end portions of a plurality of pin locking holes 22 on both sides.
[0016]
Third step: The dimension h of the tip when the connection pin 18 is driven into the sub-printed wiring board 11 protrudes from the sub-printed wiring board 11 is determined by the thickness of the solder screen 24 formed on the sub-printed wiring board 11 (typically 150 μm). )) Or less than the plate thickness.
As shown in FIG. 4 (b), a solder screen 24 is brought into close contact with the sub-printed wiring board 11, and cream solder 25 is screen-printed on mounting pads for mounted electronic components. The cream solder 25 is also printed on the protruding surface of the pin 19 on the sub-printed wiring board 11.
After printing, the electronic component 12 is soldered and connected to the sub-printed wiring board 11 by heating in a reflow furnace, and the connection pins 18 and the positioning pins 19 are also connected to the sub-printed wiring board 11 at the same time.
[0017]
B: Next, the assembly of the sub printed wiring board 11 to the main printed wiring board 10 will be described.
[0018]
Fourth step: As shown in FIG. 1, a solder screen 24 is formed on the main printed wiring board 10 with connection pads at positions corresponding to the connection ends 21 of the connection pins 18 connected to the sub printed wiring board 11. And solder cream 25 is printed. The sub-printed wiring board 11 is placed on the main printed wiring board 10 on which the cream solder 25 is printed, and is heated in a reflow furnace to solder the connection end portions 21 of the connection pins 18 to the connection pads of the main printed wiring board 10. do.
[0019]
At this time, as shown in FIG. 1, the lower end portions of the plurality of positioning pins 19 fixed to the sub-printed wiring board 11 are inserted into the positioning holes 23 of the main printed wiring board 10, so that the connection end portions of the connection pins 18 are formed. 21 and the corresponding connection pads of the main printed wiring board 10 are simply and accurately positioned and connected.
[0020]
【Example】
Next, various different embodiments will be described with reference to FIGS.
FIG. 5 shows a first embodiment, in which a main printed wiring board 10 and a sub printed wiring board 11 are connected by using the connection pins 18 shown in FIGS. 3) In the case of assembling, there is shown an embodiment in which the overall finish is made as thin as possible and the heat-generating electronic components 12b are arranged on the sub-printed wiring board 11 to dissipate heat.
[0021]
That is, the escape hole 26 is formed in the lower part of the sub-printed wiring board 11, in a part of the part of the main printed wiring board 10 overlapping with the sub-printed wiring board 11 or in the whole except for the mounting position of the connection pin 18. . By using the shortest possible connection pins 18, the tall heat-generating electronic components 12b are projected from the escape holes 26 to below the main printed wiring board 10, and the short heat-generating electronic components 12b are formed. Face the escape hole 26.
With such a configuration, it is possible to reduce the thickness and improve the heat dissipation.
[0022]
FIG. 6 shows a second embodiment. In the case of assembling the main printed wiring board 10 and the sub printed wiring board 11 with the connection pins 18 (also using the positioning pins 19 as necessary), the overall finish is obtained. This embodiment shows a case where it is desired to finish as thin as possible and to perform high-density mounting.
That is, the electronic components 12 are mounted on the upper and lower surfaces of the sub-printed wiring board 11, and the electronic components 12 are also mounted on the upper surface of the main printed wiring board 10 overlapping with the lower surface of the sub-printed wiring board 11. At this time, when the tall electronic component 12a is mounted on the lower surface of the sub-printed wiring board 11, the escape hole 26 is formed in the corresponding main printed wiring board 10 so that the tall electronic component 12a is The printed wiring board 10 is protruded below. Then, the length of the connection pin 18 is selected according to the height of the electronic component 12 to be mounted at a high density, and the main printed wiring board 10 and the sub printed wiring board 11 are assembled.
With such a configuration, both thinning and high-density mounting can be achieved.
[0023]
When the tall electronic component 12a is mounted on the upper surface of the main printed wiring board 10, a relief hole 26 is formed in the corresponding sub-printed wiring board 11 so that the tall electronic component 12a is You may make it protrude above the wiring board 11. When the tall electronic components 12a are mounted on the upper surface of the main printed wiring board 10 and the lower surface of the sub printed wiring board 11, escape holes are provided in both the corresponding sub printed wiring board 11 and the main printed wiring board 10. 26, the tall electronic component 12a may be projected above the sub-printed wiring board 11 and below the main printed wiring board 10, respectively.
[0024]
FIG. 7 shows a third embodiment. In the case where the main printed wiring board 10 and the sub-printed wiring board 11 are assembled with the connection pins 18 (using the positioning pins 19 as necessary), the total area is increased. Is shown in an embodiment in which it is desired to reduce as much as possible.
That is, the main printed wiring board 10 and the sub-printed wiring board 11 have a complete two-story structure, the electronic components 12 are mounted on the upper and lower surfaces of the sub-printed wiring board 11, and the electronic The component 12 can be mounted.
[0025]
FIG. 8 shows the fourth embodiment, and shows an example in which the sub-printed wiring board 11 is arranged at a position where the notch 27 is provided at a corner of the main printed wiring board 10 as shown in FIG. .
In a normal production process without the cutouts 27 at the corners of the main printed wiring board 10, the main printed wiring board 10 is used to stabilize the sub printed wiring board 11 in the electronic component mounting process such as handling by an automatic machine. It is desirable that the sub-printed wiring board 11 be supported and mounted on at least two sides 180 degrees apart from each other.
[0026]
However, in the case where the main printed wiring board 10 has the notch 27 at the corner, it is necessary to secure stability in order to mount the sub printed wiring board 11 so as to support the sub printed wiring board 11 on two adjacent sides at right angles. For this purpose, an extended portion 28 is integrally provided at one edge portion of the main printed wiring board 10, and the extended portion 28 is provided with an integral projecting portion 29 toward the inside of the tip thereof as necessary. Provide. The connection pin 18 is set up on the sub-printed wiring board 11 at a position overlapping the two sides of the edge of the notch 27 in the main printed wiring board 10, and an auxiliary connection pin is also formed at the position overlapped with the projection 29. The main printed wiring board 10 is mounted with the connecting ends 21 and 21a of the connecting pins 18 and 18a on the two sides of the edge of the cutout 27 of the main printed wiring board 10 and the protruding portion 29. Is mounted and soldered to the main printed wiring board 10 in a horizontally stabilized state.
When the auxiliary connection pin 18a is implanted in the sub-printed wiring board 11, its connection end 21a is aligned with the direction of the connection end 21 of one of the two sides of the edge of the notch 27. It is preferable in terms of work that a plurality of connection pins can be simultaneously planted. However, when the direction of the connection end 21a is directed toward the extension 28, the tip of the connection end 21a is placed on the extension 28, so that it is not necessary to provide the integral projection 29.
Further, in the above-described embodiment, the extension portion 28 is provided integrally with the edge portion in the longitudinal direction of the main printed wiring board 10, but may be provided at the edge portion in the short direction.
After the end of the soldering step, the extension 28 is separated and removed from the cutting line 30 using a V-cut or the like. Then, since the connection pins 18 of the protrusion 29 are not soldered, the protrusion 29 is removed together with the extension 28. The connection pin 18 standing on the protruding portion 29 is cut and removed if it gets in the way.
[0027]
In the above-described embodiment, the case of a two-story structure has been described. However, by sequentially stacking the sub-printed wiring boards 11 with the connection pins 18, a multi-story structure of three or more stories can be provided. At this time, an appropriate combination of FIGS. 1 to 8 is also possible.
[0028]
【The invention's effect】
According to the first aspect of the present invention, the step of inserting and temporarily fixing the locking projection 20 at the tip of the connection pin 18 made of a conductive metal into the pin locking hole 22 of the sub-printed wiring board 11; Cream solder 25 is printed on the insertion position of the locking projection 20 on the wiring board 11 and the solder connection pad on the main printed wiring board 10 on which the L-shaped connection end 21 is mounted at the other end of the connection pin 18. And mounting the connection end 21 of the connection pin 18 on the connection pad of the main printed wiring board 10, dissolving the cream solder 25 so that the locking projection 20 of the connection pin 18 is Since the connection end 21 of the connection pin 18 is connected to the main printed wiring board 10 by surface mounting on the wiring board 11, the contact resistance can be greatly reduced as compared with the connector. It is possible to pass a large current to the wiring plates. Further, since no connector is used, the cost of parts can be reduced. Further, since the surface mounting is performed on the main printed wiring board, through-hole holes are not required, which is extremely advantageous for wiring of a multilayer printed wiring board.
[0029]
According to the second aspect of the present invention, since the positioning pins are provided in addition to the connection pins, the mounting accuracy is significantly improved by a simple process.
[0030]
According to the third aspect of the present invention, the locking projections 20 of the connection pins 18 and / or the positioning pins 19 are squashed at the tips and bulged outward at a plurality of locations, so that the pin locking holes 22 of the sub-printed wiring board 11 are formed. The connection pins 18 and / or the positioning pins 19 can be firmly temporarily fixed to the sub-printed wiring board 11, and the step of printing the cream solder 25, the step of mounting on the connection pads, and the surface The process of mounting and connecting can be performed reliably.
[0031]
According to the fourth aspect of the present invention, the protrusion of the tip end of the connection pin from the sub-printed wiring board is made substantially the same as the thickness of the solder screen. The cream solder 25 can be simultaneously printed on the connection pad and the position where the locking projection 20 of the connection pin 18 is inserted, thereby improving workability.
[0032]
According to the fifth aspect of the present invention, the solder connection is a portion where the main printed wiring board 10 and the sub-printed wiring board 11 are overlapped, and a part of the main printed wiring board 10 or the connection end 21 of the connection pin 18 is mounted. Since the escape holes 26 are formed in all parts except the pads, the thickness of the printed wiring board can be reduced, and the heat radiation effect is further improved.
[0033]
According to the sixth aspect of the present invention, the electronic component 12a, which is a tall part of the main printed wiring board 10 and the sub-printed wiring board 11, is formed on a part of the main printed wiring board 10 or the sub-printed wiring board 11. Since the escape hole 26 is formed, the printed wiring board can be mounted at a higher density.
[0034]
According to the seventh aspect of the present invention, the step of integrally providing the extending portion 28 at one edge portion of the main printed wiring board 10 and the step of connecting the connection end 21 of the connection pin 18 to the connection pad of the main printed wiring board 10 And a step of separating and removing the extending part 28 after the soldering step is completed, so that the sub-printed wiring board 11 on which the electronic components 12 are mounted is attached to the main printed wiring board. Surface mounting can be performed in a stable state at a position where the notch 27 at the corner of the plate 10 is present.
[Brief description of the drawings]
FIG. 1 is an enlarged front view, partially cut away, of a main printed wiring board 10 and a sub printed wiring board 11 mounted by a method for mounting a printed wiring board according to the present invention.
FIG. 2 is a plan view of FIG.
FIG. 3 is an explanatory view of a different example of the connection pin 18 used in the method for mounting a printed wiring board according to the present invention, wherein (a-1), (a-2) and (a-3) are connection pins, respectively. A plan view, a front view, a side view, and (b-1) and (b-3) of a metal wire having a square cross section 18 are a plan view, a side view, and a (c-) of a metal wire having a circular connection pin 18, respectively. 1) and (c-3) are a plan view and a side view of a metal wire whose connection pin 18 has a rectangular cross section, respectively. (D-1) and (d-3) are metal wires whose connection pin 18 has an elliptical cross section. 3 is a plan view and a side view of FIG.
4A is a cross-sectional view of a state in which connection pins 18 are driven into the sub-printed wiring board 11, and FIG. 4B is a cross-sectional view of a state in which cream solder 25 is printed on the connection pins 18 by a screen 24. .
FIG. 5 is a cross-sectional view showing a first embodiment constituted by the printed wiring board mounting method of the present invention.
FIG. 6 is a sectional view showing a second embodiment constructed by the method for mounting a printed wiring board according to the present invention.
FIG. 7 is a sectional view showing a third embodiment constructed by the method for mounting a printed wiring board according to the present invention.
8A and 8B show a fourth embodiment constructed by the printed wiring board mounting method of the present invention, wherein FIG. 8A is a plan view of the main printed wiring board 10 before assembling the sub printed wiring board 11, and FIG. 2) is a plan view of the main printed wiring board 10 after the sub printed wiring board 11 is assembled on the main printed wiring board 10. FIG.
FIG. 9 is a conventional front view in which a sub printed wiring board 11 is assembled on a main printed wiring board 10.
FIG. 10 is a front view showing another conventional example in which a sub printed wiring board 11 is assembled on a main printed wiring board 10.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Main printed wiring board, 11 ... Sub printed wiring board, 12 ... Electronic component, 13 ... Main printed wiring board side connector, 14 ... Sub printed wiring board side connector, 15 ... Insulator, 16 ... Pin, 17 ... Solder, 18, 18a connection pin, 19 positioning pin, 20 locking projection, 21, 21a connection end, 22 pin locking hole, 23 positioning hole, 24 solder screen, 25 cream solder, 26 ... escape holes, 27 ... notches, 28 ... extended portions, 29 ... projecting portions, 30 ... cutting lines.

Claims (7)

In the printed wiring board mounting method in which the sub-printed wiring board 11 on which the electronic component 12 is mounted is surface-mounted on the main printed wiring board 10, the locking projection 20 at the tip of the connection pin 18 made of a conductive metal is attached. The step of inserting and temporarily fixing the pin in the pin locking hole 22 of the sub-printed wiring board 11, the insertion position of the locking projection 20 in the sub-printed wiring board 11, and the connection bent at the other end of the connection pin 18 into an L-shape. A step of printing cream solder 25 on a solder connection pad of the main printed wiring board 10 on which the end 21 is mounted; and a step of mounting the connection end 21 of the connection pin 18 on a connection pad of the main printed wiring board 10. Then, the cream solder 25 is melted, the locking projection 20 of the connection pin 18 is connected to the sub-printed wiring board 11, and the connection end 21 of the connection pin 18 is connected to the main printed wiring board. Mounting method of the printed wiring board, characterized in that comprising the step of surface mounting connection 10. In the printed wiring board mounting method in which the sub-printed wiring board 11 on which the electronic component 12 is mounted is surface-mounted on the main printed wiring board 10, the locking projection 20 at the tip of the connection pin 18 made of a conductive metal is attached. Inserting and temporarily fixing the pin projection hole 20 of the tip of the positioning pin 19 into the pin engagement hole 22 of the auxiliary printed wiring board 11 and temporarily fixing the same; Printing cream solder 25 on the insertion position of the locking projection 20 on the sub-printed wiring board 11 and the solder connection pad of the main printed wiring board 10 corresponding to this position; This portion is inserted into the positioning hole 23 of the main printed wiring board 10, and the other end of the connection pin 18 is bent into an L-shaped connection end portion 21 so as to be connected to the main pre-printer. Mounting the solder paste on the connection pads of the wiring board 10, melting the cream solder 25 to form the locking projections 20 of the connection pins 18 on the sub-printed wiring board 11, and printing the connection ends 21 of the connection pins 18 on the main printed wiring board. Mounting the printed wiring board to the wiring board 10 by surface mounting. The locking projections 20 of the connection pins 18 and / or the positioning pins 19 are squashed at the tips and bulged outward at a plurality of locations, and are pressed into the pin locking holes 22 of the sub-printed wiring board 11 to be temporarily fixed. The method for mounting a printed wiring board according to claim 1 or 2, wherein: In the printed wiring board mounting method in which the sub-printed wiring board 11 on which the electronic component 12 is mounted is surface-mounted on the main printed wiring board 10, the locking projection 20 at the tip of the connection pin 18 made of a conductive metal is attached. A step of temporarily fixing the projecting dimension of the sub-printed wiring board 11 from the sub-printed wiring board 11 when inserted into the pin locking hole 22 to be substantially the same as the thickness of the solder screen 24; The main printed wiring board on which the connection pads of the electronic components 12 to be connected, the insertion positions of the locking projections 20 on the sub-printed wiring board 11, and the L-shaped connection end 21 at the other end of the connection pin 18 are mounted. A step of printing cream solder 25 on the solder connection pads of the main printed wiring board 10; Mounting the electronic component 12 mounted on the sub-printed wiring board 11 by dissolving the cream solder 25 and the locking projections 20 of the connection pins 18 on the sub-printed wiring board 11; Connecting the portion 21 to the main printed wiring board 10 by surface mounting. Thinning and heat dissipation are performed at the overlapping portion of the main printed wiring board 10 and the sub printed wiring board 11 except for a part of the main printed wiring board 10 or a solder connection pad for mounting the connection end 21 of the connection pin 18. 5. The mounting method for a printed wiring board according to claim 1, wherein an escape hole is provided. An escape hole 26 for a tall electronic component 12a for high-density mounting, which is a part where the main printed wiring board 10 and the sub-printed wiring board 11 overlap, and is part of the main printed wiring board 10 or the sub-printed wiring board 11. 5. The method for mounting a printed wiring board according to claim 1, wherein the printed wiring board is provided. In the printed wiring board mounting method in which the sub printed wiring board 11 on which the electronic component 12 is mounted is surface-mounted at a position where the notch 27 at the corner of the main printed wiring board 10 is provided, one of the main printed wiring boards 10 is provided. A step of integrally providing an extended portion 28 at an edge portion of the connector, and a step of inserting and temporarily fixing the locking projection 20 at the tip of the connection pin 18 made of a conductive metal into the pin locking hole 22 of the sub-printed wiring board 11. And the insertion position of the locking projection 20 on the sub-printed wiring board 11 and the solder connection pad on the main printed wiring board 10 on which the L-shaped connection end 21 at the other end of the connection pin 18 is mounted. A step of printing cream solder 25; a step of mounting the connection end 21 of the connection pin 18 on the connection pad of the main printed wiring board 10 and the extension 28; In a state where the wiring board 11 is horizontally stabilized with respect to the main printed wiring board 10, the cream solder 25 is melted so that the locking projections 20 of the connection pins 18 are attached to the sub-printed wiring board 11, A method of mounting a printed wiring board, comprising: a step of surface-mounting connection of a connection end portion (21) to a main printed wiring board (10); and a step of separating and removing an extension (28) after a soldering step is completed.

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