JP2002246738A - Reflow furnace and method of cooling component in reflow furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflow furnace and a method of cooling components in the reflow furnace reducing temperature unevenness of a board by evenly cooling non-heat-resistant components mounted on the board and requiring no removing work of flux. SOLUTION: The reflow furnace 1 for heating the non-heat-resistant components 101 to 104 to electrically connect them to a board P with solder 300 while transferring the board P, on which the non-heat-resistant components 101 to 104 are mounted comprises a cooling section 60 for cooling the non-heat- resistant components 101 to 104 on the board P when heating the board P by transferring it after preheating it; and the cooling section 60 comprises an air spraying section 70 for spraying air curtain for cooling to the board P along the direction of the board P separated by at some intervals, and an exhausting section 80 for taking in and exhausting the air curtain AK for cooling sprayed from the air spraying section 70.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow furnace for heating a non-heat-resistant component to electrically connect the non-heat-resistant component to the substrate while transferring the substrate on which the non-heat-resistant component is mounted. It relates to a cooling method.

[0002]

2. Description of the Related Art A board on which various circuits of an electronic device are formed, for example, a printed board (also called a printed wiring board).
, Electronic components for configuring various circuits are mounted. Examples of the mounting format of the electronic component include insertion mounting (lead component and the like) and surface mounting (chip component and the like). The mounted electronic component is electrically connected to the wiring portion of the printed board by soldering. The soldering method includes a flow soldering method and a reflow soldering method.

[0003] The flow soldering method is a method in which a printed circuit board is passed through a solder bath containing molten solder. The reflow soldering method is a method in which cream solder or the like is applied and mounted on a predetermined portion of a printed board, and then the soldered portion of the printed board is heated in a reflow furnace.

Normally, non-heat-resistant electronic components, ie, electronic components that can be soldered by the flow soldering method, and heat-resistant electronic components, ie, electronic components that cannot be successfully soldered without the reflow soldering method, They are mounted on a single printed circuit board to improve productivity and reduce size. For example, there is a case where a tuner circuit and an IF circuit of a high-frequency device part for a television receiver are configured by one printed circuit board.

FIG. 19 shows a conventional single-sided reflow furnace for cream soldering. This reflow furnace 10
00 has a preheating unit 1010 and a reflow unit 1012. The printed circuit board P is conveyed by the conveyer 1016 in the pre-heating section 1010 and the reflow section 1 along the T direction.
012. The preheating unit 1010 is a part for preheating the printed board P, and the printed board P is preheated using the heaters H1 to H5.
When the printed circuit board P passes through the preheating unit 1010, the temperature rises from room temperature to a predetermined temperature, and the cream solder is activated without applying stress to the electronic components mounted on the printed circuit board P.

[0006] The reflow unit 1012 includes a preheat unit 10
10, the reflow unit 1012
The preheated printed circuit board P is fully heated and the non-heat-resistant components are cooled. A reflow heater unit 1020 is disposed below the printed circuit board P, and the reflow heater unit 1020 heats the lower surface side of the printed circuit board P. On the upper surface side of the printed circuit board P, a cooling unit 1021
Are arranged, and the intake blower 102 of the cooling unit 1021 is provided.
Reference numeral 7 denotes a structure in which the cooling air C is supplied to the non-heat-resistant component side on the upper surface of the printed circuit board P by sucking the outside air to be cooled.

FIG. 20 shows an example of the structure of the reflow unit 1012. A large number of holes 1026 are formed in the reflow panel 1024 of the reflow heater unit 1020, and hot air HW flows through the holes 1026 to the first side of the printed circuit board P.
It is supplied to the cream solder 300 and the heat-resistant components 201 and 202 on the surface (lower surface) 1310 side. Thereby, the first surface 1
The cream solder 300 located on the side 310 is heated. On the second surface 1320 of the printed circuit board P, non-heat-resistant components 101 to 104 are mounted.
150 reaches the first surface 1310 side, and the cream solder 300 is provided.

[0008] As shown in FIG. 19, the cooling unit A 1021 applies cooling air C from the intake blower 1027 to the deflecting plate 103.
3, the cooling air C is shielded by the shielding plate 1035.
Through the opening 1037 of the second surface 13 of the printed circuit board P
The 20 non-heat-resistant parts 101 to 104 are cooled. After the cream solder 300 is heated, the printed circuit board P
Are cooled and discharged by the cooling unit 1014 shown in FIG.

[0009]

However, the structure of the reflow section 1012 of the conventional reflow furnace 1000 has the following problems. Cooling unit A102 shown in FIG.
The position of the plurality of shielding plates 1035 needs to be adjusted according to the size and characteristics of the printed circuit board P to be produced, and the way of supplying the cooling air C needs to be changed. Shield plate 1
In the vicinity of the opening 1037 of 035 and the vicinity of the lower side of the shielding plate 1035, there is a difference in temperature at the position on the second surface 1320 of the printed circuit board P. That is, at the position on the printed circuit board P corresponding to the shielding plate 1035, the shielding plate 103
Since there is radiant heat from the lower surface of 5, the temperature of the surface of the printed circuit board becomes higher than the temperature of the surface of the printed circuit board P corresponding to the opening 1037, resulting in temperature unevenness.

Since the arrangement of the non-heat-resistant components on the printed circuit board P and the size and shape of the non-heat-resistant components differ depending on the type of the printed circuit board P, the cooling air C is directed from the opening 1037 to the second surface 1320 side of the printed circuit board P. If it is supplied by directly spraying the ink, temperature unevenness occurs. Shield plate 10
Since 35 is located near the printed circuit board P, the flux contained in the cream solder 300 adheres and deposits on the lower surface side of the shielding plate 1035. For this reason, an operation for removing the adhered flux is periodically required. Therefore, the present invention solves the above-mentioned problems, uniformly cools non-heat-resistant components mounted on a substrate, reduces temperature unevenness on the substrate, and eliminates the need for flux removal work. It is intended to provide a way.

[0011]

According to a first aspect of the present invention, there is provided a reflow heater for heating a non-heat-resistant component to electrically connect the non-heat-resistant component to the substrate while transferring the substrate on which the non-heat-resistant component is mounted. A furnace, when the main heating while transporting the substrate after pre-heating the substrate, comprising a cooling unit for cooling non-heat-resistant parts of the substrate, the cooling unit,
A gas injection unit that forms a cooling gas in a curtain shape and injects the substrate at an interval along the direction of the substrate, and the curtain-shaped cooling gas injected from the gas injection unit And a discharge section for taking in and discharging the reflow furnace. In the first aspect, the cooling unit is a part that cools the non-heat-resistant parts of the board when the board is preheated and the board is fully heated while being transported. The gas ejecting section of the cooling section forms a cooling gas in a curtain shape and ejects the gas at intervals to the substrate along the direction of the substrate. The discharge part of the cooling part takes in and discharges the curtain-shaped cooling gas injected from the gas injection part. As a result, the curtain-shaped cooling gas is guided from the gas injection unit to the discharge unit, and the curtain-shaped cooling gas is directly spaced from the substrate along the direction of the substrate, and is directly applied to the substrate. Supplied without hitting. Thus, the curtain-shaped cooling gas can cool the non-heat-resistant component of the substrate without causing temperature unevenness. Moreover, since there is no portion to which the flux contained in the solder such as the cream solder adheres, the work of removing the flux is not required at all.

According to a second aspect of the present invention, in the reflow furnace according to the first aspect, the curtain-shaped cooling gas injected from the gas injection unit is formed in a direction that does not intersect the substrate. In addition, the gas injection unit and the discharge unit are arranged facing each other at a distance. According to claim 2, the curtain-shaped cooling gas injected from the gas injection unit is formed in a direction not intersecting with the substrate.
The gas injection unit and the discharge unit are arranged to face each other at a distance.

According to a third aspect of the present invention, in the reflow furnace according to the second aspect, a direction in which the curtain-shaped cooling gas injected from the gas injection unit is formed is parallel to the substrate. In the third aspect, the direction in which the curtain-shaped cooling gas injected from the gas injection unit is formed is parallel to the substrate.

According to a fourth aspect of the present invention, in the reflow furnace according to the second aspect, the solder for electrically connecting the lead of the non-heat-resistant component to the substrate is disposed on the first surface of the substrate. The non-heat-resistant component is mounted on a second surface of the substrate opposite to the first surface, and a heater for main heating the solder of the substrate is provided on the first surface of the substrate.
The gas ejection unit and the discharge unit are arranged on a surface side, and are arranged on the second surface side of the substrate. In claim 4,
The solder on the first surface side is heated by the main heating heater, and the solder is fully heated. At this time, the curtain-shaped cooling gas is formed from the gas injection unit to the discharge unit, and can cool the non-heat-resistant component on the second surface side of the substrate.

According to a fifth aspect of the present invention, in the reflow furnace according to the first aspect, the gas is room temperature air. According to the fifth aspect, the cost can be reduced by using air at room temperature as the cooling gas.

According to a sixth aspect of the present invention, there is provided a method of cooling a component in a reflow furnace for heating a non-heat-resistant component to electrically connect the non-heat-resistant component to the substrate while transferring the substrate on which the non-heat resistant component is mounted. When the main heating while transporting the substrate after pre-heating the substrate, when the cooling unit cools the non-heat-resistant component of the substrate, the gas injection unit of the cooling unit is provided with a cooling gas. Is formed in a curtain shape, and a gas injection step of injecting the substrate at an interval along the direction of the substrate, and a discharge unit for discharging the curtain-shaped cooling gas injected from the gas injection unit. And a discharging step of taking in and discharging the parts. In the sixth aspect, the cooling unit is a part that cools the non-heat-resistant components of the board when the board is preheated and the board is fully heated while being transported. The gas ejecting section of the cooling section forms a cooling gas in a curtain shape and ejects the gas at intervals to the substrate along the direction of the substrate. The discharge part of the cooling part takes in and discharges the curtain-shaped cooling gas injected from the gas injection part. As a result, the curtain-shaped cooling gas is guided from the gas injection unit to the discharge unit, and the curtain-shaped cooling gas is directly spaced from the substrate along the direction of the substrate and directly to the substrate. Supplied without hitting. Thus, the curtain-shaped cooling gas can cool the non-heat-resistant component of the substrate without causing temperature unevenness.
Moreover, since there is no portion to which the flux contained in the solder such as cream solder adheres, the work of removing the flux is not required at all.

According to a seventh aspect of the present invention, in the method for cooling a component in a reflow furnace according to the sixth aspect, the curtain-shaped cooling gas injected from the gas injection unit does not cross the substrate. In order to form in the direction, the gas injection part and the discharge part are arranged facing each other at a distance. According to claim 7, in order that the curtain-shaped cooling gas injected from the gas injection unit is formed in a direction that does not intersect with the substrate, the gas injection unit and the discharge unit are arranged facing each other at a distance. ing.

According to an eighth aspect of the present invention, in the method for cooling a component in the reflow furnace according to the seventh aspect, the direction of formation of the curtain-shaped cooling gas injected from the gas injection unit is parallel to the substrate. It is. In the eighth aspect, the direction in which the curtain-shaped cooling gas injected from the gas injection unit is formed is parallel to the substrate.

[0019]

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 furnace of the present invention, and FIG. 2 is a plan view of the reflow furnace 1 of FIG. 1 and 2, the reflow furnace 1 is also called a single-sided reflow furnace for soldering, a single-sided reflow soldering apparatus, or the like. The reflow furnace 1 is a soldering device for electrically connecting a non-heat-resistant lead component, which is an example of a non-heat-resistant component mounted on the printed circuit board P, by solder, and a cream disposed on the lower surface side of the printed circuit board P It has a feature that the non-heat-resistant lead components on the upper surface side of the printed circuit board P can be cooled while the solder surface is heated and reflowed with hot air.

In FIG. 1 and FIG. 2, a reflow furnace 1 is generally a pre-heat section (also referred to as a pre-heater zone) 1.
0, a reflow section (also referred to as a reflow zone) 20, an exhaust / cooling zone 30, and a conveyor 40. The conveyor 40 is arranged in the T1 direction of the reflow furnace 1, and the preheating unit 10, the reflow unit 20, and the exhaust / cooling zone 30 are sequentially arranged along the T1 direction, which is the feed direction of the conveyor 40. . As a result, the printed circuit board P on which various predetermined electronic components are mounted is moved from the introduction section 40A of the conveyor 40 to the preheating section 10, the reflow section 20, and the exhaust / cooling zone 3.
After passing through 0, it is discharged from the discharge unit 40B. One of the part 40A and the part 40B of the conveyor 40 is T1
By moving in a direction perpendicular to the direction, the conveyor 40 has a structure in which the interval can be changed according to the size of the printed circuit board P.

First, the structure of the preheating unit 10 will be described. The preheating section 10 is a section for preheating the printed circuit board P, and includes preheaters 10A, 10B, 10B.
C, 10D, and 10E. Preheater 10A
And 10D are facing each other, and preheaters 10B and 10E
Is also facing. Preheater 10A, 10B, 10C
Are located below the conveyor 40, and the preheaters 10D and 10E are located above the conveyor 40. Although not shown, the preheating unit 10 further includes a circulation fan and the like, and the circulation fan has a function of supplying air to each preheater and circulating hot air. The preheating unit 10 having such a configuration is used to increase the temperature of the printed circuit board P conveyed by the conveyor 40 from room temperature to a predetermined temperature.
Is gradually heated in three stages along, for example, a T1 direction which is a feeding direction of the printed circuit board P by the conveyor 40 in the illustrated example. This makes it possible to simultaneously activate the printed board P and the non-heat-resistant components and the heat-resistant components mounted on the printed board P without applying stress.

Next, the structure of the reflow unit 20 will be described with reference to FIGS. The reflow section 20 is a system for performing main heating and cooling of the printed circuit board P preheated in the preheating section 10. Reflow unit 20
Has a structure in which the lower surface of the printed circuit board P on which the heat-resistant components are mounted is heated as necessary and the non-heat-resistant components on the upper surface of the printed circuit board P are cooled at the same time. For this purpose, as shown in FIG. 1, the reflow unit 20 includes a reflow heater 50 and a cooling unit 6.
It has 0. The reflow heater 50 is located below the conveyor 40, and the cooling unit 60 is
It is located above 0.

FIG. 3 is an enlarged side view showing the structure around the reflow section 20, and FIG. 4 is a plan view of FIG. 3 and 4, in the reflow section 20, the reflow heater 50 is located below the conveyor 40, and the cooling section 60 is located above the conveyor 40. FIG. 4 mainly illustrates the cooling unit 60 of the reflow unit 20.

First, the reflow heater 50 will be described. FIG. 5 shows an example of a cross-sectional structure taken along line AA in FIG. In FIG. 5, the reflow heater 50 is located below the conveyor 40, and a reflow panel 52 is disposed between the conveyor 40 and the reflow heater 50. For example, the reflow panel 52 shown in FIG.
As illustrated in (D), the reflow panel 52 is a plate-shaped member, and has a plurality of holes 52A. The heat generated by the reflow heater 50 becomes hot air, passes through the hole 52A of the reflow panel 52, and is supplied upward, that is, in a direction substantially perpendicular to the T1 direction which is the conveying direction of the conveyor 40, and is supplied to the conveyor. It can be heated by spraying on the cream solder 300 on the first surface 310 side of the printed circuit board P.

The printed circuit board P is transported in the direction T1 by the conveyor 40 as shown in FIG. 5, and the first surface 310 of the printed circuit board P is on the lower surface side.
On the surface 310, heat-resistant components 201 and 202 are mounted. The heat-resistant components 201 and 202 are components such as IC (integrated circuit) chips. On the other hand, non-heat-resistant lead components 101 to 104, which are non-heat-resistant components, are mounted on the second surface 320 on the upper surface side of the printed circuit board P. Lead 15 of each non-heat-resistant lead part 101-104
0 is guided to the first surface 310 side, and the cream solder 3
00 is attached. The hot air HW heats the cream solder 300. As described above, when the first surface 310 side of the printed circuit board P is heated by the hot air HW, the second surface 320 is heated.
Since the non-heat-resistant lead parts 101 to 104 on the side are non-heat-resistant parts, it is necessary to lower the temperature of the parts.
For this reason, the cooling unit 60 is connected to the second surface 3 of the printed circuit board P.
The non-heat-resistant lead components 101 to 104 on the 20 side are cooled.

The cooling section 60 has a gas injection section 70 and a discharge section 74 as schematically shown in FIGS. 4, 5 and 6. The gas injection unit 70 is also called an air nozzle, and the gas injection unit 70 is connected to an air supply source 76. The air supply source 76 has an air filter 78, and the air supply source 76 sucks normal-temperature air through the air filter 78. Since the air filter 78 is provided, dust, dust, and the like contained in air at normal temperature can be removed. The room temperature air thus cleaned is supplied from the air supply source 76 to the gas injection unit 70, and the gas injection unit 70 forms the air curtain AK using the clean room temperature air. As a result, air at a normal temperature is injected toward the cooling exhaust duct 80 of the discharge unit 74.

Here, an example of the structure of the gas injection section 70 of FIG. 6 will be described. FIGS. 8 and 9 more specifically show an example of the shape of the gas injection unit 70 called an air nozzle. The gas injection unit 70 has a structure as shown in FIG. 9A as an example of a cross-sectional structure taken along line BB in FIG. 8 includes side plates 72 and 74, a chamber 76, a member 78 for forming an air curtain shown in FIG.
80. Both ends of the chamber 76 have side plates 72,
Closed at 74. The side plate 72 has an air supply port 84 for supplying air. The air supplied from the air supply port 84 passes through the chamber 76, and the members 78,
The gas is injected from the gas injection port 86 between 80.

The portions 88 and 90 of the chamber 76 are formed so as to be inclined.
8, 80 are fixed by screws or the like. Members 78, 8
0 is such that the position can be adjusted along the FA direction and the FB direction, for example. Thereby, the opening width of the gas injection port 86 can be changed. Gas injection port 86
Are formed along the longitudinal direction of the chamber 76.
The longitudinal direction of the chamber 76 is parallel to the T1 direction for transporting the printed circuit board P.

As shown in FIGS. 9A and 9B, the ends 90 and 92 of the members 78 and 80 form gas injection ports 86. The gas injection port 86 has a shape as shown in FIGS. 8 and 5, and needs to jet the air curtain AK toward the cooling exhaust duct 80 so as to be substantially parallel to the printed circuit board P on the conveyor 40. There is. The air curtain AK shown in FIG. 8 preferably has a line L2 on the lower end surface that is substantially parallel or parallel to the plane line L1 of the printed circuit board P. The air curtain AK is an air curtain having an upper end surface 98 having a predetermined angle θ with respect to the lower end surface 96 of the air curtain along such a line L2. As shown in FIG. It is a curtain. For this purpose, as shown in FIG. 9B, it is preferable to change the angle at which the end portion 90 of the member 78 is formed and the angle at which the end portion 92 of the member 80 is formed. With such a structure, the air curtain AK is formed and ejected in a curtain shape along a direction E perpendicular to the direction T1 which is the transport direction of the printed circuit board P.

The cooling exhaust duct 80 and the gas injection section 70 shown in FIG. 4 are arranged parallel to the direction T1 and are spaced apart. As shown in FIG. 5, a front reflow exhaust duct 24a is arranged below the gas injection unit 70, and the cooling exhaust duct 8
A rear reflow exhaust duct 24b is arranged below the lower part 0.

As shown in FIGS. 3 and 4, the cooling exhaust duct 80 is connected to the facility exhaust port 100, and a sirocco fan 101 is provided in the middle thereof. By operating the sirocco fan 101, the air of the air curtain AK can be forcibly discharged from the facility exhaust port 100 to the outside via the cooling exhaust duct 80.

Next, the exhaust / cooling zone 30 shown in FIGS. 1 and 2 has a cooling fan 104. The cooling fan 104 is located on the upper side and the lower side of the conveyor 40, and the printed circuit board P that has been preheated and fully heated is cooled by the cooling fan 104 and discharged in the T1 direction.

Next, a method of one-sided soldering of the printed circuit board P using the above-described reflow furnace 1 and a cooling direction of the non-heat-resistant parts in the reflow furnace will be described. First, the processing shown in FIGS. 7A to 7C is performed on the printed circuit board P. The first surface 310 of the printed circuit board P has heat-resistant components 201 and
02 is mounted, and the cream solder 300 is mounted by the nozzle 301. As shown in FIG. 7B, after the printed circuit board P is turned over and the first surface 310 is turned downward, as shown in FIG. To 104 are implemented. The lead 150 of each non-heat-resistant lead component 101 is exposed on the first surface 310, and the cream solder 300 is located there.

The printed circuit board P on which the components are mounted as described above
7 (C), that is, the second state of the printed circuit board P
The printed circuit board P is mounted on the conveyor 40 with the surface 320 facing upward as shown in FIG. The printed circuit board P is transported in the T1 direction together with the conveyor 40, so that the printed circuit board P
Are preheated using the preheaters 10A to 10E. Accordingly, the temperature of the printed circuit board P is gradually increased from room temperature to a predetermined temperature, thereby alleviating the thermal stress of the printed circuit board P and the heat-resistant and non-heat-resistant parts mounted on the printed circuit board P, and reducing the temperature of the cream solder 300. Activation is performed.

Subsequently, the printed circuit board P is placed on the conveyor 40.
When entering the reflow section 20 from the preheat section 10 by
As shown in FIG. 7D, the printed circuit board P passes between the reflow panel 52 and the air curtain AK. At this time, the hot air HW from the reflow heater 50 is supplied to the first surface 310 side of the printed circuit board P through the hole 52A of the reflow panel 52. By supplying hot air HW to the first surface 310 through the plurality of holes 52A of the reflow panel 52 so as to be uniform, the cream solder 300 is heated and melted.

On the other hand, together with the heating and melting of the cream solder 300, in the cooling section 60, the gas jetting section 70 jets the air curtain AK to the cooling exhaust duct 80. Thus, the air curtain AK cools the non-heat-resistant lead components 101 to 104, thereby preventing the non-heat-resistant lead components 104 from being damaged by the heat history. As shown in FIG.
When K passes in the E direction, the normal-temperature air cools the second surface side of the printed circuit board P, is sucked into the cooling exhaust duct 80 side, and is forcibly discharged from the facility exhaust port 100.

FIGS. 10 and 11 are sectional views taken along the line AA in FIG. FIG. 10 shows an example in which the printed circuit board P is transported by the conveyor 40 and is located below the air curtain AK, and FIG.
Indicates a state in which it is not located below the air curtain AK. In both FIG. 10 and FIG. 11, the gas injection unit 70 injects the air curtain AK toward the cooling exhaust duct 80 at high speed along the E direction. In this case, the hot air HW passing through the reflow panel is refracted by hitting the lower surface, which is the first surface of the printed circuit board P, as indicated by the dashed arrow, and most of the hot air HW is discharged through the front reflow exhaust duct 24a. The air is sucked into the rear reflow exhaust duct 24b.

Air curtain AK from gas injection unit 70
Is passed through the upper surface, which is the second surface of the printed circuit board P, at a high speed, so that the second surface 3 shown in FIG.
The non-heat-resistant lead components 101 to 104 on the 20 side are kept at a low temperature and can exert a cooling effect. This is considered to be the same phenomenon that the temperature becomes lower without receiving the wind directly on the back side of the fan.

In FIG. 11, the printed circuit board P is no longer under the air curtain AK. In this case, the hot air HW passing through the hole of the reflow panel 52 is used.
Is released upward once. However, the air curtain AK becomes a curtain shape and the reflow panel 52 is operated at high speed.
Most of the hot air HW flows through the rear reflow exhaust duct 24 b and the cooling exhaust duct 80.
And a part of the hot air HW is sucked into the front reflow exhaust duct 24a. Front reflow exhaust duct 24a
Then, the hot air sucked into the rear reflow exhaust duct 24b is discharged to the outside from the facility exhaust port 100 by the operation of the sirocco fan 101 shown in FIG.

FIG. 12 shows the temperature of the non-heat-resistant lead component on the second surface 320 of the printed circuit board P shown in FIG.
The example which measured the temperature of the cream solder 300 of the 1st surface 310 side is shown. FIG. 12A shows a temperature curve M of the non-heat-resistant lead component and a temperature curve N of the cream solder 300 in the component cooling method according to the present invention. FIG.
(B) shows the temperature curve S of the non-heat-resistant lead component and the temperature curve U of the cream solder in the conventional cooling method. As is apparent from a comparison between FIG. 12A and FIG.
Even if there is a rise in the temperature of the solder curve N and the temperature of the solder curve U, the temperature of the part J of the temperature curve M of the component shown in FIG.
It can be seen that the temperature is at the same level as the temperature of the part K of the temperature curve S of the part 2 (B). In both FIGS. 12 (A) and 12 (B), the peak portion of the cream solder temperature curve has a pseudo trapezoidal shape due to the equipment for lead-free soldering.

Next, another embodiment of the reflow furnace of the present invention will be described. In the embodiment shown in FIG. 4, the gas injection unit 70 and the cooling exhaust duct 80 are arranged in parallel at a predetermined interval d along the direction T1 which is the direction of transport of the printed circuit board P.

In the embodiment of the reflow furnace shown in FIG. 13, the gas injection section 170 of the reflow section 20 and the cooling exhaust duct 18
0 are arranged at an interval d1 in parallel to a direction E perpendicular to the direction of transport T1 of the printed circuit board P. Due to such a structure, the gas injection unit 170 is provided with an air curtain AK.
Is injected along the T1 direction and is guided to the cooling exhaust duct 180.

In another embodiment of the reflow furnace of FIG. 14, the cooling exhaust duct 80 of the reflow section 20 is the same as the cooling exhaust duct 80 of FIG. However, the structure of the gas injection unit 270, also called an air nozzle, is different. The gas injection section 270 is, for example, of a long cylindrical type as shown in FIG. 16, and has an injection port 286 formed along the axial direction. An end of the gas injection unit 270 is closed, and an air supply port 84 is provided at one end. In the example of FIG. 14, the gas injection unit 270 and the cooling exhaust duct 74 are parallel to the T1 direction and are arranged at an interval d2.

In another embodiment of the reflow furnace shown in FIG. 15, a gas injection unit 27 having a structure similar to that of the gas injection unit shown in FIG.
0 and the cooling exhaust duct 280 are arranged at an interval d3 from each other along a direction orthogonal to the T1 direction.

FIGS. 17 and 18 show another example of the gas injection section 270, which has a long cylindrical shape. The gas injection unit 270 has an injection port 48 having a certain length in the example of FIG.
6 are arranged in series in the axial direction. The gas injection unit 270 of FIG. 18 includes a plurality of, for example, circular injection ports 38.
6.

In the embodiment of the reflow furnace of the present invention, as shown in FIG. 10, the air curtain AK sprayed from the gas spraying section 70 can be sprayed substantially in parallel without being directly sprayed on the printed circuit board P. Figure 7 of P
The non-heat-resistant lead parts 101 to 101 on the second surface 320 shown in FIG.
104 or the like can be cooled almost uniformly. In addition, since the gas is not directly blown onto the component, the component does not tilt due to wind pressure.

The reflow furnace according to the embodiment of the present invention is a single-sided reflow furnace, and is a soldering device for electrically connecting non-heat-resistant lead components mounted on a substrate. The solder surface at the bottom of the board is heated by hot air and reflowed, and at the same time, the non-heat-resistant components on the top face of the board are cooled. A thin air curtain runs parallel to the board at high speed in the horizontal direction above the component surface of the mount board. The air curtain blocks the heat that diffuses upward. Heat shielding to the upper portion prevents the upper surface of the substrate, that is, the component surface, from being heated. A cooling effect is obtained by preventing the heating of the component surface.

By employing the reflow furnace of the present invention, it is not necessary to adjust the position of the intake shielding plate when changing the shape and size of the substrate or the quantity and size of the mounted components. Since the air curtain AK is used, the temperature unevenness on the component surface can be significantly reduced. Eliminates design constraints such as the assembly state of mounted components on the board. The abolition of the shield plate eliminates the problem of flux contamination and eliminates the need for cleaning the shield plate.

The present invention is not limited to the above embodiment. The shape of the gas injection unit, which is also called an air nozzle, is not limited to the illustrated example, and it is of course possible to adopt another shape. The type of gas in the form of an air curtain to be injected from the gas injection unit is not limited to low-cost normal-temperature air, but also slightly lower-than-normal-temperature air or a type of gas other than air, such as N ₂ gas which is an example of an inert gas. Of course, it does not matter even if is used. When such an inert gas is used, it is desirable to circulate the gas instead of discharging it from the facility exhaust port.

[0051]

As described above, according to the present invention,
The non-heat-resistant components mounted on the substrate are uniformly cooled to reduce the temperature unevenness on the substrate, and the work of removing the flux becomes unnecessary. Further, there is no restriction on the design of the substrate, and the condition setting on the equipment side can be simplified.

[Brief description of the drawings]

FIG. 1 is a side view showing a preferred embodiment of a reflow furnace of the present invention.

FIG. 2 is a plan view of the reflow furnace of FIG.

FIG. 3 is an enlarged view mainly showing a reflow portion of the reflow furnace of FIG. 1;

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a diagram showing an example of a cross-sectional structure taken along line AA of FIG. 4;

FIG. 6 is a plan view of FIG. 5;

FIG. 7 is a diagram showing a state in which a non-heat-resistant component, a heat-resistant component, and a cream solder are mounted on a printed circuit board and the non-heat-resistant component is cooled by an air curtain when the cream solder is heated by a reflow process.

FIG. 8 is a perspective view showing examples of the shapes of a gas injection unit and an air curtain.

FIG. 9 is a cross-sectional view taken along the line BB of FIG. 8 showing a structural example of the gas injection unit.

FIG. 10 is a diagram illustrating a state in which a printed circuit board is located below an air curtain in a reflow unit.

FIG. 11 is a diagram illustrating a state in which a substrate is not positioned below an air curtain in a reflow unit.

FIG. 12 is a diagram showing a temperature of a non-heat-resistant component in the embodiment of the present invention and a temperature of a non-heat-resistant component in a comparative example (conventional method).

FIG. 13 is a view showing another embodiment of the reflow furnace of the present invention.

FIG. 14 is a view showing still another embodiment of the reflow furnace of the present invention.

FIG. 15 is a view showing still another embodiment of the reflow furnace of the present invention.

FIG. 16 is a view showing another embodiment of the gas injection section in the reflow furnace of the present invention.

FIG. 17 is a view showing still another embodiment of the gas injection unit.

FIG. 18 is a view showing still another embodiment of the gas injection section of the present invention.

FIG. 19 is a view showing a conventional reflow furnace.

FIG. 20 is a diagram showing a state in which a non-heat-resistant component is conventionally cooled.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reflow furnace, 10 ... Preheating part (preheating part), 20 ... Reflow part (main heating part), 40 ...
・ Conveyor, 50 ・ ・ ・ Reflow heater, 60 ・ ・
・ Cooling unit, 70 ・ ・ ・ Gas injection unit (air nozzle) 、 7
4 ... discharge part, 80 ... cooling exhaust duct, 101-
104: non-heat-resistant component, 201, 202: heat-resistant component, 300: cream solder, 310: first surface of printed circuit board, 320: second surface of printed circuit board,
AK: air curtain (an example of curtain-shaped cooling gas), P: printed circuit board (substrate)

Claims (8)

[Claims] 1. A reflow furnace for heating a non-heat-resistant component while electrically transporting the substrate on which the non-heat-resistant component is mounted, to electrically connect the non-heat-resistant component to the substrate by soldering. When the main heating is performed while transporting the substrate, a cooling unit that cools the non-heat-resistant component of the substrate is provided, and the cooling unit forms a cooling gas in a curtain shape along the direction of the substrate. A reflow furnace, comprising: a gas injection unit that injects the substrate at an interval, and a discharge unit that takes in and discharges the curtain-shaped cooling gas injected from the gas injection unit. 2. The method according to claim 1, wherein the curtain-shaped cooling gas injected from the gas injection unit is formed in a direction that does not intersect the substrate.
The reflow furnace according to claim 1, wherein the reflow furnaces are arranged to face each other at a distance. 3. The reflow furnace according to claim 2, wherein a direction in which the curtain-shaped cooling gas injected from the gas injection unit is formed is parallel to the substrate. 4. The first surface of the substrate is provided with the solder for electrically connecting leads of the non-heat-resistant component to the substrate, and a second surface of the substrate opposite to the first surface. The non-heat-resistant component is mounted on the substrate, a heater for the main heating of the solder of the substrate is disposed on the first surface side of the substrate, and the gas ejecting unit and the discharging unit are provided on the substrate. The reflow furnace according to claim 2, which is arranged on the second surface side. 5. The air according to claim 1, wherein the gas is air at a normal temperature.
The reflow furnace according to 1. 6. A method for cooling a component in a reflow furnace, which heats the non-heat-resistant component to electrically connect the substrate with the substrate by soldering while transporting the substrate on which the non-heat-resistant component is mounted. When preheating the main board while transporting the board after preheating, when the cooling section cools the non-heat-resistant parts of the board, the gas injection section of the cooling section forms a cooling gas in a curtain shape. A gas injection step of injecting the substrate at an interval along the direction of the substrate, and a discharge step of taking in and discharging the curtain-shaped cooling gas injected from the gas injection unit by a discharge unit. When,
A method for cooling parts in a reflow furnace, comprising: 7. The gas injection unit and the discharge unit, wherein the curtain-shaped cooling gas injected from the gas injection unit is formed in a direction that does not intersect the substrate.
The method for cooling components in a reflow furnace according to claim 6, wherein the components are arranged to face each other at a distance. 8. The method for cooling components in a reflow furnace according to claim 7, wherein a direction in which the curtain-shaped cooling gas injected from the gas injection unit is formed is parallel to the substrate.