JPH08204325A - Accurately mounting method for electronic component - Google Patents

Abstract

PURPOSE: To provide a method for accurately mounting an electronic component in which leads can be accurately positioned to a pad when a surface mounting type electronic component (QFP) is mounted on a printed board in a method for mounting the component on the board. CONSTITUTION: When a surface mounting type electronic component is mounted on a board by reflow soldering, a hanging base 10 is installed across the component mounted on the board, reflow soldering is conducted in the state that a hanging force is applied to the component via a spring 11 from the base 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting electronic components on a printed circuit board, and more particularly to a high precision mounting method for mounting a surface mount electronic component (QFP) on a printed circuit board.

In recent years, as electronic devices have been miniaturized and electronic parts have been mounted at a high density, packages of electronic parts such as LSI elements are provided with a large number of narrow-pitch terminal pieces (hereinafter referred to as leads). Became.

When mounting such a package having a large number of leads on a printed circuit board, each lead is positioned with respect to a pad provided on the printed circuit board and soldered to fix it. It is designed to make electrical connections.

When mounting electronic components, it is necessary to accurately position the tip of each lead at a predetermined position during soldering work so that highly accurate mounting can be realized.

[0005]

2. Description of the Related Art Generally, an automatic mounting apparatus is used for mounting electronic parts, and a mounting robot for transferring electronic parts automatically positions it on a substrate fixed on the apparatus. The method of mounting electronic components is used.

However, in such a positioning method, depending on the moving accuracy of the table on which the printed circuit board is mounted and the positioning accuracy of the mounting robot that carries the electronic components, the electronic components are provided at a fine pitch. It is difficult to accurately position the lead of the above with respect to a predetermined pad of the printed circuit board.

On the other hand, conventionally, there is known a method of automatically and highly accurately positioning a surface mounting type electronic component (QFP) by reflow soldering.

FIG. 8 shows an example of a conventional high-accuracy mounting method for electronic components, showing a positioning method by reflow soldering. In the figure, (a) shows before soldering, and (b) shows after reflow soldering.

As shown in FIG. 8A, the printed circuit board 1
When the solder paste 3 made of cream solder is printed on the pad 2 in advance and the lead 5 of the QFP 4 is placed on the pad 2 and the whole is heated, when the QFP 4 is small and lightweight, the component load of the lead 5 on the pad 2 Since the (surface load) is small, when the solder paste 3 printed on the pad 2 is melted, the lead 5 automatically moves to the pad 2 as shown in FIG. 8B due to the self-alignment effect based on the surface tension of the solder. Since it is positioned in the center of the solid state and is fixed by the solidified solder 6 as it is, the problem of displacement does not occur.

[0010]

In the conventional method shown in FIG. 8, in the case of a small and lightweight QFP, the self-alignment effect based on the surface tension of the molten solder causes
Highly accurate mounting of electronic components can be realized. However, when the QFP is large and heavy, it is difficult to mount electronic parts with high precision by such a method.

FIG. 9 illustrates reflow soldering for a large and heavy electronic component.
Shows before soldering, and (b) shows after reflow soldering.

As shown in FIG. 9 (a), a large and heavy QF having a radiation fin 7 is attached in the same manner as in FIG.
Even if the lead 5 of P4 is placed on the pad 2 on the printed board 1 and the solder paste 3 printed on the pad 2 is melted, the surface load of the portion of the lead 5 is large. The self-alignment effect of the pad 2 and the lead 5 cannot be obtained as shown in FIG. 9B.
It becomes difficult to perform high-precision mounting because a state in which the positional deviations between the two are caused and the state where they are fixed by the solidified solder 6 is likely to occur.

On the other hand, a protrusion is made to protrude below the center of gravity of the electronic component, and the protrusion is directly or indirectly point-contacted with the mounting board to support the electronic component and soldered on the board conductor. There is known a method of obtaining a self-alignment effect at the time of reflow soldering by preventing a weight load from being applied to an electronic component lead to be attached.

However, in such a mounting component supporting method by point contact, there is a problem that the dimensional accuracy of the protruding portion that supports the component is required to be strict. FIG. 10 shows the influence of the difference in height of the protrusions,
(A) shows a normal state, (b) has shown the case where a protrusion part is too high.

As shown in FIG. 10 (a), when the height of the projection 8 is proper, the lead 5 of the QFP 4 does not give a heavy load to the pad 2 on the printed board 1, A self-alignment effect can be obtained during reflow soldering. On the other hand, as shown in FIG. 10B, when the height h of the protrusion 8 is larger than the reference value, the lead 5 floats or tilts with respect to the pad 2 and becomes An unsoldered portion 9 is likely to occur between the pads 2. On the other hand, when the height of the protrusion 8 is smaller than the reference value, a sufficient self-alignment effect cannot be expected.

The present invention is intended to solve such a problem of the prior art, and reduces the surface load between the pad and the lead at the time of reflow soldering of electronic parts to reduce the surface tension of the molten solder. It is an object of the present invention to provide a highly accurate mounting method for electronic components, which can ensure the positioning of leads based on the self-alignment effect of the above.

[0017]

[Means for Solving the Problems]

(1) In the method of mounting a surface mount type electronic component on a substrate by reflow soldering, a lifting platform 10 is installed across the electronic components placed on the substrate, and the spring 1 is mounted on the lifting platform.
Reflow soldering is performed with a lifting force being applied to the electronic component via 1.

(2) In the board mounting method of the surface mount type electronic component by reflow soldering, the magnet 17 is mounted on the upper surface of the electronic component, and the magnet mounting jig 15 is mounted across the electronic component placed on the substrate. The reflow soldering is performed in a state where the magnet is installed and another magnet 16 is held directly above the magnet 17 by a magnet mounting jig so that different poles face each other.

(3) In the method of mounting a surface mount type electronic component on a substrate by reflow soldering, a magnet 17 is attached to the upper surface of the electronic component, and another magnet 18 is placed below the substrate corresponding to the electronic component placed on the substrate. Reflow soldering is performed with the same poles held so that they face each other.

(4) In the method of mounting a surface mount type electronic component on a substrate by reflow soldering, the electronic component is mounted on the lower surface of the electronic component and is slightly smaller than the distance between the lower surface and the upper surface of the substrate when the electronic component is mounted on the substrate. It has long hair-like fibers 20.

(5) In the method of mounting a surface mount type electronic component on a substrate by reflow soldering, an arbitrary number of through holes 26 are provided at the electronic component mounting position on the substrate, and the through hole is provided through an air hose 25 attached to the lower part of the substrate. Reflow soldering is performed in a state where compressed air is blown onto the lower surface of the electronic component placed on this substrate.

(6) In the method of mounting a surface mount type electronic component on a substrate by reflow soldering, a copper land 3 surrounded by a frame 31 made of a water repellent resin is provided at a position where the electronic component is mounted on the substrate.
0 is provided and solder is supplied onto this copper land, and then reflow soldering of the electronic component placed on the substrate is performed.

(7) In the method of mounting a surface mount type electronic component on a substrate by reflow soldering, the electronic component has a solder pool 38 filled with solder at a connection portion between each lead 37 and an internal circuit. During reflow soldering, the solder in the solder pool is melted so that the leads can move.

[0024]

[Action]

(1) Lifting stand 10 straddling electronic parts placed on the board
Is installed, and the electronic components are heated by applying a hoisting force to the electronic components from the hoisting base through the springs 11 to reflow solder the pads 2 to which the solder paste 3 is applied in advance and the leads 5 of the electronic components. Do.

Since the surface load between the lead 5 and the pad 2 at the time of reflow soldering can be reduced by the lifting force for the electronic component, the lead can be produced by the self-alignment effect based on the surface tension of the molten solder on the pad 2. 5 can be positioned in the center of the pad 2 and soldered.

(2) The magnet 17 is mounted on the upper surface of the electronic component, and the magnet mounting jig 15 is installed straddling the electronic component placed on the substrate, and the magnet 17 is mounted directly on the magnet 17. By heating another magnet 16 while holding different poles facing each other, reflow soldering is performed between the pad 2 to which the solder paste 3 is applied in advance and the lead 5 of the electronic component.

The attraction force between the magnet 17 attached to the electronic component and the magnet 16 held by the magnet attaching jig reduces the surface load between the lead 5 and the pad 2 during reflow soldering. Because you can
Due to the self-alignment effect based on the surface tension of the molten solder on the pad 2, the lead 5 can be positioned and soldered in the center of the pad 2.

(3) The magnet 17 is attached to the upper surface of the electronic component, and at the same time, another magnet 18 is heated at the bottom of the substrate corresponding to the electronic component placed on the substrate so that the same poles face each other. Depending on the solder paste 3
The reflow soldering of the pad 2 coated with and the lead 5 of the electronic component is performed.

A magnet 17 mounted on the upper surface of the electronic component
And the repulsive force with another magnet 18 provided on the lower part of the substrate, the surface load between the lead 5 and the pad 2 at the time of reflow soldering can be reduced.
Due to the self-alignment effect based on the surface tension of the molten solder, the lead 5 can be positioned and soldered in the center of the pad 2.

(4) On the lower surface of the electronic component, the hair-like fibers 20 which are slightly longer than the distance between the lower surface and the upper surface of the substrate when the electronic component is mounted on the substrate are planted. By heating such an electronic component placed on the substrate, reflow soldering is performed between the pad 2 to which the solder paste 3 is applied in advance and the lead 5 of the electronic component.

Hairy fibers 2 provided on the lower surface of the electronic component
The elastic force of 0 causes the electronic component to be lifted from the substrate surface, so that the surface load between the lead 5 and the pad 2 at the time of reflow soldering can be reduced. Due to the self-alignment effect based on the surface tension, the lead 5 can be positioned in the center of the pad 2 and soldered.

(5) An arbitrary number of through holes 26 are provided at the electronic component mounting positions on the board. The pad 2 to which the solder paste 3 is applied in advance by heating the compressed air from the through hole through the air hose 25 attached to the lower part of the substrate while blowing it onto the lower surface of the electronic component placed on the substrate.
And reflow soldering with the lead 5 of the electronic component.

The compressed air blown to the lower surface of the electronic component through the through hole 26 receives a force for lifting the electronic component from the substrate surface, so that the surface between the lead 5 and the pad 2 at the time of reflow soldering. The load can be reduced, and the lead 5 can be positioned and soldered in the center of the pad 2 by the self-alignment effect based on the surface tension of the molten solder on the pad 2.

(6) A copper land 30 surrounded by a frame 31 made of a water-repellent resin is provided at a position where electronic components are mounted on the board. After the solder is supplied onto the copper land, the electronic component is placed on the substrate and heated to reflow solder the pad 2 to which the solder paste 3 is applied in advance and the lead 5 of the electronic component.

Since the electronic component receives buoyancy based on the surface tension of the molten solder on the copper land, the surface load between the lead 5 and the pad 2 at the time of reflow soldering can be reduced, and the melting on the pad 2 can be reduced. Due to the self-alignment effect based on the surface tension of the solder, the lead 5 can be positioned and soldered in the center of the pad 2.

(7) Solder pool 3 filled with solder at the connection between each lead 37 of the electronic component and the internal circuit
8 is provided. By heating the electronic component placed on the substrate, reflow soldering is performed between the pad 2 to which the solder paste 3 is applied in advance and the lead 5 of the electronic component.

At the time of reflow soldering of electronic parts, the solder in the solder pool 38 is melted and the leads 37 are brought into a movable state. Therefore, the leads 37 are moved by the self-alignment effect based on the surface tension of the molten solder on the pads 2. It can be positioned and soldered in the center of the pad 2.

[0038]

[Embodiment] FIG. 1 shows an embodiment (1) of the present invention, in which a spring is used to suspend the QFP to reduce the surface load between the pad and the lead, thereby promoting the self-alignment effect. An example of doing so is shown. In the figure,
The same parts as those in FIG. 8 are indicated by the same numbers, 10 is a hoist, 11 is a spring, 12 is a holding portion for holding the QFP,
13 is a hook.

The solder paste 3 is printed in advance on the pad 2 on the printed circuit board 1, and the lead 5 of the QFP 4 is placed thereon. At this time, the lifting table 10 is installed across the QFP 4 and the spring 11 coupled to the lifting table 10 is installed.
The hook 1 on the holding part 12 attached to the QFP4.
3 so that the lifting force by the spring 11 acts on the QFP 4 during reflow soldering.

In this state, the lifting force F expressed by the following equation acts on QFP4. F = kx k: spring constant x: amount of spring extension Therefore, by setting the lifting force F according to the weight of the QFP 4, the surface load between the lead 5 and the pad 2 can be reduced, The self-alignment effect is promoted.

For example, if a lifting force of 10 g is required, the following spring may be used. Now, when using a spring with a spring constant of 0.02 kg / cm, 0.01 (kg) = 0.02 (kg / cm) x 0.5
Since it is (cm), the QFP 4 may be lifted with the spring extended by 5 mm.

FIG. 2 shows an embodiment (2) of the present invention, in which buoyancy is applied to the QFP by using magnetism to reduce the surface load between the pad and the lead, and the self-alignment effect. This is an example of promoting the above. In the figure, (a) shows a case where the attractive force of the magnet is used,
(B) shows the case where the repulsive force of the magnet is used. In the figure, the same parts as those in FIG. 8 are indicated by the same numbers, 15 is a magnet attachment jig, 16 is a first magnet attached to the jig 15, 17 is a second magnet fixed to the QFP 4, and 18 Is a third magnet provided under the printed circuit board 1.

In FIG. 2A, the first magnet 16 is
The magnet attaching jig 15 fixes the N pole and the S pole so that they are vertically arranged. The second magnet 17 is also fixed to the QFP 4 so that the N pole and the S pole are vertically arranged. Therefore, since different poles of the magnets 16 and 17 face each other, an attractive force acts on each other, and a buoyant force is exerted on the QFP 4 so that the QFP 4 can be pulled upward.
The surface load between them can be reduced, and the self-alignment effect is promoted.

Further, referring to FIG. 2B, the printed circuit board 1
The third magnet 18 provided in the lower part of the is fixed so that the S pole and the N pole are vertically arranged. Therefore, the magnets 17, 1
In No. 8, since the same poles face each other, repulsive forces act on each other and buoyancy acts such that the QFP 4 is pushed upward, so that the surface load between the lead 5 and the pad 2 can be reduced.

FIG. 3 shows an embodiment (3) of the present invention, in which buoyancy is applied to the QFP by utilizing the elastic force of the hair-like fibers on the lower surface of the QFP, and the surface between the pad and the lead is This is an example in which the load is reduced to promote the self-alignment effect. In the figure, (a) shows before soldering and (b) shows after soldering. In the figure, the same parts as those in FIG.
Is a hairy fiber planted in the lower part of the QFP 4, and is attached so that the tip of the fiber is in contact with the printed board 1.

As shown in FIG. 3A, the QF when the QFP 4 is mounted on the printed circuit board 1 on the bottom surface of the QFP 4.
Insulation heat resistant hair-like fibers such as glass fibers having a length slightly longer than the distance between the lower surface of P4 and the upper surface of the printed circuit board 1, for example, (the height from the bottom surface of the QFP4 to the lower surface of the lead 5) +100 μm. Plant 20 and fix. Therefore, before soldering, QFP4 has 20
Due to the elastic force of the buoyancy, the buoyancy that lifts the printed circuit board 1 from the surface is applied.

When heated in this state, when the solder paste 3 printed on the pad 2 is melted, the QFP 4 becomes
Therefore, the surface load between the lead 5 and the pad 2 is reduced, and the self-alignment effect is generated. In this state, the solidified solder 6 causes the self-alignment effect, as shown in FIG. 3C. , The lead 5 and the pad 2 are fixed.

FIG. 4 shows an embodiment (4) of the present invention, in which air is blown from the bottom of the QFP to give buoyancy to the QFP and reduce the surface load between the pad and the lead.
This is an example of promoting the self-alignment effect. In the figure, 25 is an air hose provided under the QFP 4, 26 is an arbitrary number of through holes provided in the printed circuit board 1, and 27 is an air flow.

As shown, when an air hose 25 is applied to the lower surface of the printed circuit board 1 and compressed air is sent, an air flow 27 is generated upward from the through hole 26 provided in the printed circuit board 1 and the QFP 4 is pushed upward. To be For example, φ1m
About 20 m holes are provided and the air pressure is 2.0 kg / cm.
^When compressed air is sent as ² , buoyancy of about 10 g acts on the QFP 4, so the surface load between the lead 5 and the pad 2 is reduced, and the self-alignment effect is promoted.

FIG. 5 is a diagram showing the structure of the substrate surface in the embodiment (5) of the present invention, and FIG. 6 is a diagram showing the soldering method in the embodiment (5) of the present invention. In the embodiment (5), the expressed tension of the solder in the substrate area where the QFP is mounted is used to give the buoyancy to the QFP, reduce the surface load between the pad and the lead, and promote the self-alignment effect. It shows an example. In FIG. 6, (a) shows a state before soldering, (b) shows a state of supplying solder to the copper land, and (c) shows a state after soldering. In each figure, the same parts as those in FIG. 8 are indicated by the same numbers, 30 is a copper land provided in the lower part of the QFP 4, 31 is a frame made of a water-repellent resin such as Teflon provided around the copper land 30, Reference numeral 32 is a solder dispenser, 33 is a molten solder supplied to the copper land 30 by the solder dispenser 32, and 34 is a solder on the copper land 30 after soldering.

As shown in FIG. 5, the copper land 30 is formed by printing on the lower surface of the central portion of the QFP body of the printed board 1. Around the copper land 30, the copper land 3
A frame 31 made of a water-repellent resin is formed so as to surround 0.

When electronic parts are mounted, FIG. 6 (a)
As shown in FIG. 6, the solder paste 3 is printed on the pad 2 in advance, and then, as shown in FIG. 6B, before the QFP is mounted, the molten solder 33 is supplied onto the copper land 30 by the solder dispenser 32. To do. Next, when the QFP 4 is mounted and reflow soldering is performed, the surface tension of the molten solder 33 on the copper land causes a buoyant force on the QFP 4, and the surface load between the lead 5 and the pad 2 is reduced. At the same time, in this state, the lead 5 and the pad 2 are fixed by the solidified solder 6 in a state where the self-alignment effect is produced by the surface tension of the molten solder on the pad 2.

FIG. 7 shows an embodiment (6) of the present invention, showing an example in which terminals are highly accurately connected by the self-alignment effect of the movable terminals. In the drawing, (a) is a partial cross-sectional structural view in the vertical direction of the QFP according to the present invention, (b) is a partial cross-sectional structural view in the horizontal direction before soldering of the QFP according to the present invention, and (c) is the present invention. FIG. 3D is a partial cross-sectional structural view in the lateral direction of the QFP after soldering, and FIG. 3D is a terminal structural view of the conventional QFP shown for comparison. The same parts as those in FIG. 8 are indicated by the same numbers, 36 is a conventional QFP lead, 37 is a QFP lead according to the present invention,
38 is a solder pool in the QFP.

The lead 36 of the conventional QFP is shown in FIG.
As shown in FIG. 5, the wire from the internal chip of the QFP and the lead 36 are connected by bonding and then fixed by resin.
Is reflow soldered to the pad 2 using the solder paste 3.

On the other hand, each lead 37 of the QFP according to the present invention is movable, and one end of the lead 37 is mounted inside the QFP 4 before the printed circuit board is mounted.
Inside, it is fixed by solder, and at the same time, it is connected to the internal circuit via solder. Lead 37 is Q
During the reflow soldering of the FP 4, as the solder paste 3 on the pad 2 melts, the solder in the solder pool 38 also melts, and the leads 37 mainly move laterally. Therefore, before the reflow soldering of the QFP 4, even if there is a gap between the lead 37 and the pad 2, the lead 37 moves during the reflow soldering as shown in FIG. By Figure 7
As shown in (c), the solder in the solder pool 38 and the solder in the portion of the pad 2 are solidified and fixed in the state of being correctly positioned with respect to the pad 2.

[0056]

As described above, according to the present invention, the surface mount type electronic component (QF) is manufactured by reflow soldering.
When P) is mounted on a printed circuit board, soldering can be performed with the tip portions of the leads of the QFP properly positioned at predetermined positions, so that highly accurate mounting of electronic components can be realized. It will be possible.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment (1) of the present invention.

FIG. 2 is a diagram showing an embodiment (2) of the present invention, in which (a)
Shows the case where the attractive force of the magnet is used, and (b) shows the case where the repulsive force of the magnet is used.

FIG. 3 is a diagram showing an embodiment (3) of the present invention, in which (a)
Shows before soldering, and (b) shows after soldering.

FIG. 4 is a diagram showing an embodiment (4) of the present invention.

FIG. 5 is a diagram showing a configuration of a substrate surface in an embodiment (5) of the present invention.

FIG. 6 is a diagram showing a soldering method in an embodiment (5) of the present invention, in which (a) is a state before soldering and (b) is
Shows the supply state of solder to the copper land, and (c) shows the state after soldering.

FIG. 7 is a diagram showing an embodiment (6) of the present invention, in which (a)
Is a vertical partial sectional structure view of the QFP according to the present invention,
(B) is a lateral partial sectional structure diagram of the QFP according to the present invention before soldering, (c) is a lateral partial sectional structure diagram of the QFP according to the present invention after soldering, (d) is a comparison FIG. 6 is a terminal structure diagram of a conventional QFP shown for the purpose of FIG.

FIG. 8 is a diagram showing an example of a conventional high-accuracy mounting method for electronic components, (a) showing before soldering and (b) showing after reflow soldering.

9A and 9B are diagrams illustrating reflow soldering for a large and heavy electronic component, in which FIG. 9A shows before soldering, and FIG. 9B shows after reflow soldering.

10A and 10B are diagrams showing the influence of the difference in height of the protrusions, where FIG. 10A shows a normal state, and FIG. 10B shows a case where the protrusions are too high.

[Explanation of symbols]

 10 Lifting Platform 11 Spring 15 Magnet Mounting Tool 16 Magnet 17 Magnet 18 Magnet 20 Hair Fiber 25 Air Hose 26 Through Hole 30 Copper Land 31 Frame 37 Lead 38 Solder Pool

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mamoru Shinshiro 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Yasuhiro Tejima 1015, Kamedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited ( 72) Inventor Hideaki Terauchi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (7)

[Claims] 1. A method of mounting a surface mount type electronic component on a substrate by reflow soldering, wherein a lifting platform is installed across the electronic component placed on the substrate, and the electronic component is mounted on the lifting platform via a spring. A high-precision mounting method for electronic components, characterized by performing reflow soldering while applying a lifting force. 2. A method of mounting a surface mount electronic component on a substrate by reflow soldering, wherein a magnet is mounted on the upper surface of the electronic component, and a magnet mounting jig is installed across the electronic component placed on the substrate. A high-accuracy mounting method for electronic components, characterized in that reflow soldering is performed in a state in which another magnet is held immediately above the magnet by the magnet mounting jig so that different poles face each other. 3. A method of mounting a surface mount electronic component on a substrate by reflow soldering, wherein a magnet is attached to an upper surface of the electronic component and another magnet is attached to a lower portion of the substrate corresponding to the electronic component placed on the substrate. A high-precision mounting method for electronic components, characterized in that reflow soldering is performed while holding the electrodes so that they face each other. 4. A method of mounting a surface mount type electronic component on a substrate by reflow soldering, wherein the electronic component is on the lower surface of the electronic component, and the distance between the lower surface and the upper surface of the substrate when the electronic component is mounted on the substrate is slightly greater. A high-precision mounting method for electronic components, which has long hair-like fibers. 5. A method of mounting a surface mount type electronic component on a substrate by reflow soldering, wherein an arbitrary number of through holes are provided at electronic component mounting positions on the substrate, and compressed from the through hole through an air hose attached to a lower portion of the substrate. A high-accuracy mounting method for electronic components, characterized in that reflow soldering is performed while air is blown onto the lower surface of the electronic components placed on the substrate. 6. A method of mounting a surface mount electronic component on a substrate by reflow soldering, wherein a copper land surrounded by a frame made of a water-repellent resin is provided at a position where the electronic component is mounted on the substrate, and solder is placed on the copper land. A high-precision mounting method for electronic components, comprising reflow soldering of electronic components placed on a substrate after supply. 7. A method of mounting a surface mount electronic component on a substrate by reflow soldering, wherein the electronic component has a solder pool filled with solder at a connecting portion between each lead and an internal circuit, and the reflow of the electronic component is performed. A high-accuracy mounting method for an electronic component, characterized in that the solder in the solder pool is melted during soldering and the leads are brought into a movable state.