JP2002158434A - Apparatus and method for reflow soldering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for reflow soldering in which a heat resistant device can be connected electrically and mechanically to a substrate with high reliability, while reducing the size, even when lead free solder is used. SOLUTION: A reflow soldering apparatus 1 for connecting a heat resistant device electrically to a substrate P mounting a heat resistant device on at least the first or second side thereof by passing the substrate P along the flow direction comprises a section 10 for preheating the first and second sides of the substrate P, a reflow section 11 for sustaining the peak temperature of the substrate P by supplying hot wing HW uniformly to the preheated substrate P, and a section 12 for cooling the substrate P passed through the reflow section 11 wherein the reflow section 11 is disposed between the preheat section 10 and the cooling section 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reflow soldering apparatus and a reflow soldering method for performing soldering for electrically connecting a heat-resistant component to a substrate.

[0002]

2. Description of the Related Art Reflow soldering is known as a mounting technique for mechanically fixing an electronic component such as a surface-mounted device on a printed circuit board by conductive connection using solder. In reflow soldering technology, the terminals of the device are aligned and mounted on a printed circuit board on which solder paste has been printed in advance, and the board is heated by passing it through a reflow furnace, thereby melting the solder and applying the device to the printed circuit board. Solder the terminals. In such a reflow soldering technique, a reflow soldering device is used. This reflow soldering apparatus is an apparatus in which a heat-resistant component is mounted on at least one of one surface and another surface of a printed circuit board, and terminals of the heat-resistant component are electrically soldered to a conductor pattern of the printed circuit board. It is also called a double-sided reflow soldering apparatus or a tunnel reflow furnace.

In this reflow soldering apparatus, the solder on one side and the other side of a printed circuit board is heated and reflowed by hot air, and then the heat-resistant parts of the printed circuit board are cooled to cool and solidify the solder. . In this type of reflow soldering apparatus, when the printed circuit board flows through the preheating section and the reflow section of the reflow soldering apparatus, one side and the other side of the printed circuit board are heated by a heater, and the temperature of the printed circuit board gradually increases. As the temperature rises, the temperature of the substrate reaches a peak value in the final portion of the reflow portion. Thereafter, the printed circuit board is cooled in the cooling zone. A conventional reflow soldering apparatus has a temperature profile as described above. In other words, this temperature profile has a so-called single-peak curve characteristic in which the temperature of the printed circuit board reaches a peak at the final portion of the reflow portion, and thereafter, the temperature of the printed circuit board drops rapidly in the cooling zone.

FIG. 15 shows an example of a conventional reflow soldering apparatus. The conventional reflow soldering apparatus has a preheating unit 1000, a reflow unit 1001, and a cooling unit 1002. The printed circuit board P is heated by heaters 1004 above and below the pre-heating unit 1000 and then heated and cooled by the heaters 1 above and below the reflow unit 1001.
005 further heats. And the printed circuit board P
Is rapidly cooled by the cooling fan 1006 of the cooling unit 1002.

[0005]

When soldering is performed by a conventional reflow soldering apparatus, particularly when a lead-free solder is used as the solder, for example, a preheating section 1000 having heaters of 7 to 9 zones and a reflow section 1001 are used. Is required to be able to maintain the peak of the temperature of the printed circuit board for a certain period of time, so that the reflow soldering apparatus becomes a very large facility. The single-peak curve temperature profile of the conventional reflow furnace for leaded solder has insufficient temperature as a soldering condition for lead-free solder. Insufficient temperature causes reliability problems such as poor soldering leakage. As described above, a reflow furnace compatible with lead-free solder is a multi-zone large-scale facility having 7 to 9, so that the cost is greatly increased (about 1.5 to 2 times). Replacing all equipment with a lead-free reflow furnace would be a huge capital investment. In addition, the old equipment is wasted in disposal, and as a result, the cost of the product is increased and the problem of processing the old equipment occurs. Therefore, the present invention solves the above-mentioned problems, and when using lead-free solder, even if this lead-free solder is used, the heat-resistant component can be electrically and mechanically securely connected to the substrate, and downsizing can be achieved. An object of the present invention is to provide a reflow soldering apparatus and a reflow soldering method.

[0006]

According to the first aspect of the present invention, there is provided the following:
By passing the substrate on which the heat-resistant component is mounted on at least one of the surface and the second surface along the flow direction,
In a reflow soldering apparatus that performs soldering for electrically connecting the heat-resistant components, a preheating unit that preheats the first surface and the second surface of the substrate, and a preheating unit that preheats the substrate. After further heating, a reflow unit for uniformly supplying hot air to maintain the peak temperature of the substrate, and a cooling unit for cooling the substrate that has passed through the reflow unit, the reflow unit, A reflow soldering device is provided between the preheating unit and the cooling unit. In claim 1,
The preheating unit preheats the first surface and the second surface of the substrate. After further heating the preheated substrate, the reflow unit supplies hot air uniformly to maintain the peak temperature of the substrate. The cooling unit cools the substrate that has passed through the reflow unit. The reflow section is arranged between the preheating section and the cooling section. With this, after preheating in the preheating section, the reflow section further heats the preheated substrate and raises the temperature of the solder to the peak temperature,
By supplying hot air uniformly, the peak temperature of the substrate is maintained. By maintaining the peak temperature of the substrate in this way, it is possible to eliminate insufficient temperature when soldering a heat-resistant component to the substrate using lead-free solder instead of leaded solder. In addition, unlike the conventional method, the reflow section that supplies hot air uniformly to maintain the peak temperature of the substrate between the preheating section and the cooling section can reduce the size of the device unlike the conventional method. Cost can be reduced.

According to a second aspect of the present invention, in the reflow soldering apparatus according to the first aspect, the reflow portion includes a uniform hot air supply device for uniformly supplying hot air to the preheated substrate. According to claim 2, the reflow unit has a uniform hot air supply device, and the uniform hot air supply device includes:
Hot air is uniformly supplied to the preheated substrate.

According to a third aspect of the present invention, in the reflow soldering apparatus according to the first aspect, the reflow portion is configured so that the hot air is supplied to the substrate by the uniform hot air supply device. A heater for further heating the first surface and the second surface; According to the third aspect, the reflow unit has a heater that further heats the first and second surfaces of the substrate before hot air is supplied to the substrate by the uniform hot air supply device. Thus, the lead-free solder on the first and second surfaces of the substrate is raised to the peak temperature, and the peak temperature is maintained by the hot air of the uniform hot air supply device. By maintaining the peak temperature, it is possible to suppress a rise in the temperature of the component, and there is also an advantage in terms of component reliability.

According to a fourth aspect of the present invention, in the reflow soldering apparatus according to the second aspect, the uniform hot air supply device includes an air supply unit, a heating unit for heating air from the air supply unit, and the heating unit. A hot air uniform section for uniformly supplying hot air from the section to the substrate side. In claim 4, the heating unit of the uniform hot air supply device heats the air from the air supply unit. The hot air uniform section uniformly supplies hot air from the heating section to the substrate side.

According to a fifth aspect of the present invention, in the reflow soldering apparatus according to the fourth aspect, the hot air uniform portion has a heat emitting member having a large number of holes and a stirring device for stirring the hot air blown out from the heat emitting member. And a panel for uniformly blowing the stirred hot air from a number of holes onto the substrate. In claim 5, the stirring section of the hot air uniform section is
The hot air blown from the heat releasing member is stirred. The panel is
Stirred hot air is uniformly blown from a number of holes onto the substrate. As a result, almost the same peak temperature can be maintained over the entire substrate.

According to a sixth aspect of the present invention, in the reflow soldering apparatus according to the fifth aspect, the panel has the holes having a uniform size.

According to a seventh aspect of the present invention, in the reflow soldering apparatus according to the sixth aspect, the arrangement pitch of the holes of the panel with respect to the flow direction of the substrate is equal to the flow direction of the substrate in the holes of the panel. It is set to twice the arrangement pitch in the orthogonal direction. According to the seventh aspect, the arrangement pitch of the holes of the panel in the flow direction of the substrate is set to twice (or sparse pitch) the arrangement pitch in the direction orthogonal to the flow direction of the substrate. The rise stops, a small waveform curve is formed, the peak temperature can be maintained, and a temperature profile suitable for lead-free soldering can be formed.

[0013] The invention according to claim 8 is to electrically connect the heat resistant components by passing a substrate having heat resistant components mounted on at least one of the first surface and the second surface along a flow direction. A preheating step of preheating the first surface and the second surface of the substrate by a preheating unit, and further heating the preheated substrate. Thereafter, a peak temperature maintaining step of uniformly supplying hot air from a reflow unit to maintain the peak temperature of the substrate, and a cooling step of cooling the substrate that has passed through the reflow unit by a cooling unit, This is a reflow soldering method. In a preferred embodiment, in the preheating step, the first and second surfaces of the substrate are preheated by the preheating unit. In the peak temperature maintaining step, hot air is uniformly supplied from the reflow section to the pre-heated substrate to maintain the peak temperature of the substrate. In the cooling step, the substrate that has passed through the reflow unit is cooled by the cooling unit. Thus, after preheating in the preheating section, the reflow section further heats the preheated board, raises the temperature of the solder to the peak temperature, and then supplies hot air uniformly to the board, thereby preheating the board. Maintain peak temperature. By maintaining the peak temperature of the substrate in this way, it is possible to eliminate insufficient temperature when soldering a heat-resistant component to the substrate using lead-free solder instead of leaded solder.
In addition, unlike the conventional method, the reflow section that supplies hot air uniformly and maintains the peak temperature of the substrate between the preheating section and the cooling section allows the apparatus to be simpler and smaller than before. , Can greatly reduce costs.

According to a ninth aspect of the present invention, in the reflow soldering method according to the eighth aspect, a hot air is uniformly supplied to the preheated substrate from a uniform hot air supply device. According to the ninth aspect, the reflow unit has a uniform hot air supply device, and the uniform hot air supply device uniformly supplies hot air to the preheated substrate.

According to a tenth aspect of the present invention, in the reflow soldering method according to the eighth aspect, the heater of the reflow portion is provided before the hot air is supplied to the substrate by the uniform hot air supply device of the reflow portion. The first surface and the second surface of the substrate are heated. In a tenth aspect, before the hot air is supplied to the substrate by the uniform hot air supply device, the reflow unit further heats the first surface and the second surface of the substrate by the heater. The lead-free solder on the first and second surfaces of the substrate is raised to a peak temperature, and the peak temperature is maintained by hot air from a uniform hot air supply device.

[0016]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 is a side view showing a preferred embodiment of the reflow soldering apparatus of the present invention, and FIG. 2 is a plan view of the reflow soldering apparatus. The reflow soldering apparatus 1 is also called, for example, a double-sided reflow soldering apparatus or a tunnel reflow furnace. The reflow soldering apparatus 1 roughly includes a preheating unit 10,
It has a reflow section 11, a cooling section 12, and a conveyor 13, and these preheat section 10, reflow section 1
1, the cooling unit 12 and the conveyor 13 are located in the main body 100.

A conveyor 13 is provided along the preheating section 10, the reflow section 11 and the cooling section 12. The conveyor 13 can feed a printed board P as an example of a board along a flow direction T. As a result, the printed circuit board P on which the predetermined heat-resistant components are mounted can be discharged from the introduction section IN of the conveyor 13 to the outside through the preheating section 10, the reflow section 11, the cooling section 12, and the discharge section OUT.

As shown in FIG. 2, the conveyor 13 has a front conveyor 13a for carrying the printed circuit board P thereon.
And the rear conveyor 13b.
a is fixed so as not to move in the U direction, and the rear conveyor 13b is movable in the U direction. Thereby, the rear conveyor 13b is connected to the printed circuit board P.
The printed circuit boards P of various sizes can be conveyed along the flow direction T by adjusting the width in accordance with the width of the printed circuit board.

Next, the preheating unit 10 shown in FIGS.
Will be described. The preheating section 10 is a zone for preheating the printed circuit board P,
A plurality of heaters are arranged vertically above and below. The preheat section 10 has, for example, a preheater 10A, a preheater 10B, and a preheater 10C. FIG.
The preheater 1 is located below the conveyor 13 as shown in FIG.
0A, 10B, and 10C are arranged along the flow direction T. Similarly, preheaters 10A, 10B, and 10C are arranged along the flow direction T above the conveyor 13. Upper preheater 10A, 10B, 1
0C heats the upper surface side of the printed circuit board P. The lower preheaters 10A, 10B, and 10C are printed circuit boards P
Heat the lower surface of.

The pre-heaters 10A, 10B and 10C of the pre-heating section 10 having the above-described structure increase the temperature of the printed circuit board P conveyed on the conveyor 13 from room temperature to a predetermined temperature of, for example, 180 ° C. In addition, heating is performed gradually over three stages.
This makes it possible to simultaneously activate the lead-free cream solder on the printed board without applying thermal stress to the printed board and heat-resistant components such as electronic components mounted on the printed board.

Next, the structure of the reflow unit 11 shown in FIGS. 1 and 2 will be described. The reflow section 11 has a first reflow section 20 and a second reflow section 30. The first reflow section 20 is a section for raising the solder surface of the printed circuit board P preheated by the preheating section 10 to a peak reflow temperature. As shown in FIG. 1, the first reflow section 20 has a heater 20A and another heater 20B. The heater 20 </ b> A is arranged next to the preheater 10 </ b> C below the preheating unit 10, and the upper heater 20 </ b> B is arranged next to the preheater 10 </ b> C above the preheating unit 10. Therefore, below the conveyor 13, the preheaters 10A, 10B, and 10C of the preheating unit 10 and the heater 20A of the first reflow unit 20 are arranged in the flow direction T. Similarly, the preheaters 10A, 10B, and 10C of the preheating unit 10 on the upper side of the conveyor 13 and the heater 20B of the first reflow unit 20 are arranged along the flow direction T.

The second reflow section 30 includes a first reflow section 2
After the solder surface of the printed circuit board is raised to the peak temperature of the reflow temperature at 0, the reflow peak temperature is maintained (keeped) and the printed circuit board is heated according to the pseudo trapezoidal temperature profile. When the printed circuit board P preheated in the preheating section 10 enters the first reflow section 20, the first reflow section 20 gradually heats the solder surface of the printed circuit board P, and the lead-free cream solder of the printed circuit board P At the end of the reflow section 20, the reflow peak temperature is reached. Therefore, the second reflow unit 30 supplies hot air HW to the solder surface having the peak reflow temperature as shown in FIG. 1 to maintain a state where the peak temperature of the reflow temperature is maintained for a certain time. Thus, heat-resistant parts are soldered according to a predetermined temperature profile.

FIG. 3 is a side view showing the reflow section 11, and the second reflow section 30 has a uniform hot air supply device 150. The structure of the uniform hot air supply device 150 is shown in FIGS. FIG. 4 is a side view of the uniform hot air supply device 150 of FIG. 3 viewed from the direction E, FIG. 5 is a plan view of the uniform hot air supply device 150 of FIG. 4, and FIG.
FIG. 2 is a side view of the uniform hot air supply device 150 viewed from the direction F. As shown in FIG. 4, the uniform hot air supply device 150 includes an air supply unit 41, a heating unit 42, and a hot air uniform unit 43. The uniform hot air supply device 150 is located above the conveyor 13 as shown in FIG.

The air supply section 41 supplies air into the heating section 42. 4 to 6 and 7.
As shown in (A) and (B), a heat release member 44 and a heater 45 are provided. The heater 45 includes a heat releasing member 44.
Is supplied in the portion 49 of FIG. 2, and is supplied with a current from the power supply 46 to heat the air passing through the heat releasing member 44 to generate hot air. This heater 45
Is, for example, a coil-shaped heater. FIG. 7 (A),
As shown in (B), a large number of holes 48 are formed in the portion 47 of the heat release member 44. From these holes, the hot air HW can be blown out of the heat releasing member 44. The heat releasing member 44 may be in the shape of a tube or another shape.

As shown in FIG. 8, a hole 48 of the heat releasing member 44 is provided.
Are formed at equal intervals in the radial direction.
8, the hot air HW can be uniformly discharged in all directions.

As shown in FIGS. 4 and 5, two heat emitting members 44 are provided side by side on the upper portion of the hot air uniform portion 43. That is, the portion 47 of the heat release member 44 is
3 is housed in the surge tank 31. The axial direction of the heat release member 44 is a direction orthogonal to the flow direction T of the conveyor 13 as shown in FIGS. 4 and 5, for example. The hot air uniform part 43 in FIG.
And a surge tank 31 and a panel 50 that are hot air agitating sections. As shown in FIGS. 4 and 6, the surge tank 31 has a heater section 31A and a hot air stirring section 31B. The heater portion 31A accommodates the portions 47 of the two heat release members 44 described above. Stirrer 31B
Is located below the heater section 31A, and has a function of stirring, uniformly dispersing the hot air emitted from the hole 48 of the heat emitting member 44 of the heater section 31A, and sending it to the panel 50 side. The stirring section 31B has a first tank 60 and a second tank 62. First tank 60 and heater section 31A
A first mesh 63 for stirring with hot air is disposed between the first and second meshes. A second mesh 64 for stirring hot air is disposed between the second tank 62 and the first tank 60.

The hot air HW supplied from the heater enters the first tank 60 after being further stirred by the first mesh 63, and the hot air is further stirred by the second mesh 64.
Then, the mixture is further stirred and enters the second tank 62.
The hot air that has entered the second tank 62 passes through the holes 70 of the panel 50, is further uniformly stirred and dispersed, and is then supplied to the printed circuit board P on the conveyor 13 shown in FIG. By supplying the hot air HW to the solder surface of the printed circuit board P, the first reflow unit 20 in FIG. 3 maintains the state where the reflow temperature reaches the peak temperature.

Next, the panel 50 shown in FIGS. 4 and 5 will be described with reference to FIG. The panel 50 is also called a reflow panel, and is, for example, a rectangular panel. The panel 50 is made of a material having heat resistance, for example, titanium, brass, steel or the like. The panel 50 has a number of holes 70. This hole 70
The arrangement pitch is 2 m in the direction and the arrangement pitch is m in the Y direction. The X direction is a direction parallel to the flow direction T of the printed circuit board P, and the Y direction is a direction orthogonal to the flow direction T. That is, the hole 7 of the panel 50
The arrangement pitch of the zero substrate in the flow direction T is set to twice the arrangement pitch of the holes of the panel in the direction orthogonal to the flow direction of the substrate. By setting such a pitch, the temperature rise in the second reflow portion is stopped, a small waveform curve is obtained, the peak temperature can be maintained almost under the equipment conditions, and a temperature profile suitable for lead-free soldering is formed. Becomes possible. If the temperature further rises in the second reflow, a problem of component reliability occurs.

The hole 70 of the panel 50 in FIG. 9 is, for example, a circular hole, but is not limited to this, and may be a hole of another shape such as a square hole. In the example of FIG.
The arrangement pitch of the holes 70 in the X direction is a sparse pitch arrangement, whereas the arrangement pitch of the holes 70 in the Y direction is dense.

FIG. 10 shows another embodiment of the panel 50. The panel 50 of FIG.
have. The arrangement pitch in the X direction of the rectangular holes 70 is 2 m, and the arrangement pitch in the Y direction is m. Also in this case, the arrangement pitch of the holes 70 in the X direction is sparse,
The arrangement pitch of the holes 70 in the Y direction is small.

Here, an example of the printed circuit board P conveyed by the conveyor of FIG. 1 will be described. In the example of FIG. 11A, the printed circuit board P has the heat-resistant component 20 on the first surface 310 side.
1 is mounted. However, no heat-resistant components are mounted on the second surface 320. In the example of the printed circuit board P in FIG. 11B, the heat-resistant component 201 is not mounted on the first surface 310, but the heat-resistant component 201 is mounted on the second surface 320. In the example of FIG. 11C, the heat-resistant component 201 is mounted on both the first surface 310 and the second surface 320 of the printed circuit board P. Examples of the heat-resistant component include a chip component such as a resistor, a capacitor, a transistor, and an IC (integrated circuit). The reflow soldering apparatus 1 shown in FIGS. 1 and 2 can perform soldering of the heat-resistant components of the printed circuit board P of such a type.

Next, an example of the structure of the cooling unit 12 shown in FIG. 1 will be briefly described. The cooling unit 12 has a cooling fan 12a. The cooling fan 12a is located above the conveyor 13 and prints cooling air supplied from the outside by the conveyor 13 for example. By spraying the printed circuit board P, the printed circuit board P is rapidly cooled.

Next, a reflow soldering method using the reflow soldering apparatus 1 shown in FIGS. 1 and 2 will be described with reference to FIGS. 12, 13 and 14. First, FIG.
In the preheating step ST1, the printed circuit board P shown in FIG. 1 passes through the preheating section 10 along the flow direction T by the conveyor 13. The printed circuit board P includes pre-heaters 10A, 10B, 1
After gradually preheating by 0C, it reaches the reflow unit 11 in FIG. Each preheater 1 of the preheat section 10
0A to 10C are obtained by preheating the lead-free cream solder 300 of the printed circuit board P shown in FIG.
The first first reflow section 20 raises the solder surface of the solder 300 to the peak temperature of the reflow. In the preheating unit 10 of FIG. 1, the lead-free cream solder 300 is raised to, for example, 150 ° C. to 180 ° C. during the time t1, as shown in FIG. Then, in the peak temperature maintaining step ST2 of FIG. 12, the printed circuit board P is connected to the reflow unit 11 of FIG.
After passing through the first reflow section 20, the solder surface of the lead-free cream solder is, for example, from 180 ° C. to 23 ° C. during the time t2.
The temperature is raised to a temperature slightly higher than 5 ° C.

When the printed circuit board P passes through the second reflow section 30 of FIG. 1 after the printed circuit board P has passed through the first reflow section 20 as described above, the printed board P is Hot air H through hole 70
W is sprayed uniformly. This allows the printed circuit board P
The lead-free cream solder maintains a peak temperature state of reflow (keeps) and is heated by a pseudo-trapezoidal temperature profile PF as shown in FIGS.

In this case, as shown in FIG. 4 or FIG.
The air from the air supply unit 41 is turned into hot air HW by the heater 45 of the heating unit 42. The hot air HW is a heat releasing member 44.
As shown in FIG. 8, the liquid is uniformly discharged from the hole 48 in the entire circumferential direction. The discharged hot air passes through the first mesh 63 from the heater section 31A and enters the first tank 60, and further passes through the second mesh 64 and enters the second tank 62. The hot air HW entering the second tank 62 is the first mesh 6
3 and the second mesh 64 are uniformly dispersed and agitated.
From 0, the heated and homogenized hot air HW is
Is sprayed on the printed circuit board P. From this, the solder surface of the lead-free cream solder on the printed circuit board P is maintained at the predetermined peak temperature for the time t3.

As described above, the printed circuit board P preheated by the preheating section 10 is carried into the reflow section 11 by the conveyor 13 and is printed by the first reflow section 20.
Is heated further from the preheating (preheating) temperature and rises, and when the solder surface has finished flowing through the first reflow portion 20, the reflow temperature substantially reaches the peak of the specified temperature. When entering the second reflow section 30, it is heated at a constant pitch by the hot air HW from the reflow panel hole 70, so that under appropriate conditions, the temperature stops increasing and a small wave-shaped temperature curve is obtained, and the temperature at which the peak temperature is almost maintained The profile PF becomes a temperature condition suitable for lead-free soldering. That is, the reflow unit 11
By adjusting the heater temperature, hot air volume, and conveyor speed, a pseudo-trapezoidal temperature profile curve can be created. The printed circuit board P that has passed through the second reflow unit 30 in this manner passes through the cooling unit 12 of FIG. 1 in the cooling step ST3 of FIG.
As shown in FIG. 14, cooling is performed in the cooling zone by the cooling air supplied from the cooling device, and the temperature sharply decreases.

Today, lead-free solder is being introduced to cope with global environmental problems. However, investment in new equipment for a conventional large-sized reflow furnace consisting of 7 to 9 zones is large due to reasons such as solder wettability and temperature conditions. It has become a challenge. A “pseudo trapezoidal curve” that keeps a reflow peak for a certain time by adding a second reflow unit 30 between the preheating unit 10 and the cooling unit 12 due to a change or improvement of a part of the conventional equipment.
Temperature profile. As a result, a reflow soldering apparatus capable of introducing lead-free solder at a low cost, which allows for remodeling of conventional equipment, including cost reduction of a new reflow furnace, can be realized.

As a second reflow for keeping a reflow peak between the reflow zone and the cooling zone for a certain time, a surge tank shown in FIG. 3 is added. Surge tank 31
Has a hot-air blow-out panel, and holes are opened at, for example, twice the pitch in the X (flow of substrate) direction in the Y direction. In the pseudo trapezoidal curve of the reflow profile, the flat portion has a waveform with a small repetition of the temperature. The cooling zone can be installed on the line conveyor outside the equipment by modifying the conventional equipment.

By adding a second reflow section surge tank to a reflow soldering apparatus using leaded solder, a temperature profile in which lead-free solder can be used can be realized at low cost. However, in terms of space, the cooling unit 12 in FIG. 1 can be installed on a line conveyor or the like outside the equipment. O of the operation of the second reflow unit 30
Introduced lead-free solder test by switching N-OFF,
In addition, the equipment can be shared with the existing solder and lead-free solder. That is, with simple operation of the equipment, the equipment for the conventional leaded solder and the equipment for the lead-free solder can be used. The ON / OFF operation may be performed only by the heater 45 shown in FIG. 5, and the air from the air supply unit 41 becomes a cooling air, and the second reflow unit becomes a preliminary cooling zone when the current leaded solder is used.
The reflow peak is pseudo-flattened, so that the temperature of the back surface components can be lower than that of the conventional method.

The present invention is not limited to the above embodiment. In the above-described embodiment, the surge tank 31 of the uniform hot air supply device 150 has a structure including the first mesh and the second meshes 63 and 64.
Of course, one mesh or three or more meshes may be used. Instead of the surge tank 31, a type in which a sirocco fan and a heater are combined, such as a single-sided reflow furnace, can be adopted. The shape of the holes 70 in the panel 50 is not limited to a circular shape or a rectangular shape, and may be other shapes, and an arrangement pitch of holes and other types may be employed.

[0042]

As described above, according to the present invention,
When a lead-free solder is used, even if the lead-free solder is used, the heat-resistant component can be reliably electrically and mechanically connected to the substrate, and the size can be reduced. The temperature profile of the reflow section can be formed in a pseudo-trapezoidal curve, making it simple and compact as a lead-free equipment, and reducing costs.

[Brief description of the drawings]

FIG. 1 is a side view showing a preferred embodiment of a reflow soldering apparatus according to the present invention.

FIG. 2 is a plan view of the reflow soldering apparatus of FIG. 1;

FIG. 3 is a diagram showing a reflow section of the reflow soldering apparatus.

FIG. 4 shows a structural example of a uniform hot air supply device, and FIG.
The figure seen from E direction of.

FIG. 5 is a plan view of the uniform hot air supply device of FIG. 4;

FIG. 6 is a view of the uniform hot air supply device of FIG. 4 as viewed from a direction F.

FIG. 7 is a diagram showing a structural example of a heating unit.

FIG. 8 is a diagram illustrating an example of a cross-sectional structure of a heat release member of a heating unit.

FIG. 9 is a plan view showing an example of the shape of a panel.

FIG. 10 is a plan view showing a shape example of another embodiment of the panel.

FIG. 11 illustrates an example of a printed circuit board.

FIG. 12 is a flowchart showing a reflow soldering method.

FIG. 13 is a diagram showing an example of a reflow temperature profile when a lead-free solder is used.

14 is a diagram showing a pseudo-trapezoidal temperature profile in the reflow temperature profile in FIG. 13, particularly in a reflow zone.

FIG. 15 is a view showing a conventional reflow soldering apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reflow soldering apparatus, 10 ... Preheating part, 11 ... Reflow part, 12 ... Cooling part, 13
... Conveyor, 20 ... First reflow unit, 30
..Second reflow part, 31 ... surge tank, 41.
..Air supply unit, 42 heating unit, 43 hot air uniform unit, 44 heat release member, 45 heater
50 panel, 70 panel hole, 150
・ Uniform hot air supply device, HW: hot air, P: printed circuit board

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B23K 101: 42 B23K 101: 42

Claims (10)

[Claims] 1. Soldering for electrically connecting a heat-resistant component by passing a substrate having a heat-resistant component mounted on at least one of a first surface and a second surface along a flow direction. A preheating unit for preheating the first surface and the second surface of the substrate; and further uniformly supplying hot air after heating to the preheated substrate. A reflow unit for maintaining a peak temperature of the substrate, and a cooling unit for cooling the substrate that has passed through the reflow unit, wherein the reflow unit is disposed between the preheating unit and the cooling unit. A reflow soldering apparatus. 2. The reflow soldering apparatus according to claim 1, wherein the reflow section has a uniform hot air supply device for uniformly supplying hot air to the preheated substrate. 3. The reflow section includes a heater that further heats the first surface and the second surface of the substrate before hot air is supplied to the substrate by the uniform hot air supply device. 2. The reflow soldering apparatus according to 1. 4. The uniform hot air supply device, comprising: an air supply unit; a heating unit for heating air from the air supply unit; and a hot air uniform unit for uniformly supplying hot air from the heating unit to the substrate side. The reflow soldering apparatus according to claim 2, comprising: 5. The hot air uniform section includes: a heat emitting member having a large number of holes; a stirring section for stirring hot air blown from the heat emitting member; 5. The reflow soldering apparatus according to claim 4, comprising: a panel that sprays uniformly. 6. The reflow soldering apparatus according to claim 5, wherein the panel has the holes having a uniform size. 7. The arrangement pitch of the holes of the panel in the direction of flow of the substrate is set to twice the arrangement pitch of the holes of the panel in the direction perpendicular to the direction of flow of the substrate. A reflow soldering apparatus according to item 1. 8. Soldering for electrically connecting the heat-resistant component by passing a substrate having a heat-resistant component mounted on at least one of the first surface and the second surface along a flow direction. A pre-heating step of pre-heating the first surface and the second surface of the substrate by a pre-heating unit; and further heating the pre-heated substrate from the re-flow unit after heating. A reflow soldering method, comprising: a peak temperature maintaining step of uniformly supplying hot air to maintain a peak temperature of the substrate; and a cooling step of cooling the substrate having passed through the reflow unit by a cooling unit. . 9. The reflow soldering method according to claim 8, wherein hot air is uniformly supplied to the preheated substrate from a uniform hot air supply device. 10. Before the hot air is supplied to the substrate by the uniform hot air supply device of the reflow unit, the heater of the reflow unit is connected to the first surface of the substrate and the second surface.
The reflow soldering method according to claim 8, wherein the surface is heated.