JPH03198980A - Hot wind reflow device - Google Patents

Abstract

PURPOSE:To adjust the temp. profile of a work according to the heat capacity of the work by providing a work transporting line from the work feed port to ejection port of the device body, providing hot wind blow-out devices for preheating and reflow along this line and constituting the two blow-out devices in such a manner that the spacing therebetween can be varied and adjusted. CONSTITUTION:The work W feed port 12 is provided on one side face of the device body 11. The work transporting line 14 for transporting the work W is provided along the work ejection port 13 of the other side face therefrom. The hot wind blow-out devices 22, 32 for preheating and the hot wind blow-out devices 25, 35 for reflow facing the work transporting line 14 are provided. The hot wind blow-out devices 22, 32 for preheating and the hot wind blow-out devices 25, 35 for reflow are so constituted that the spacings therebetween can be varied and adjusted. The dealing with the difference in the falling speed of the preheating temp. according to the heat capacity of the work arising during the work movement is possible in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Field of Industrial Application) The present invention relates to a hot air reflow apparatus that performs reflow soldering using hot air.

(Prior art) In conventional hot air reflow equipment, in order to alleviate the heat shock during reflow of the workpiece, the workpiece being transported by the workpiece transport line is first preheated by a preheater to raise the workpiece temperature to about 150°C. Then, hot air is blown onto the workpiece, and the heat of this hot air is used to heat the workpiece to 220-230℃, reflowing the cream solder applied to the board as a workpiece, and reflowing the cream solder applied to the board as a workpiece. Electronic components such as chips are now reflow soldered.

(Problem to be solved by the invention) The heat capacity of the workpiece varies depending on the size of the board and the heat capacity of the components mounted on the board, and even if the amount of heat generated by the preheater is the same,
The temperature profile of the workpiece (workpiece temperature rise/fall characteristics) differs depending on the heat capacity of the workpiece.

For example, for a workpiece with a small heat capacity, the preheat temperature decreases relatively quickly while moving from the preheat area to the reflow area, and for a workpiece with a large heat capacity, the preheat temperature decreases relatively quickly while moving from the preheat area to the reflow area. does not change much.

On the other hand, preheating a workpiece with a small heat capacity to a higher temperature than necessary in anticipation of a rapid drop in preheating temperature goes against the purpose of preventing heat shock due to a rapid temperature rise of components mounted on the board.

For this reason, the conventional hot air reflow apparatus has a problem in that the workpiece temperature at the start of reflow does not become constant depending on the heat capacity of the workpiece.

The present invention has been made in view of these points, and an object of the present invention is to provide a hot air reflow apparatus that can adjust the temperature profile of a workpiece according to the heat capacity of the workpiece.

[Structure of the Invention] (Means for Solving the Problem) The invention of claim 1 provides a hot air reflow apparatus for blowing hot air onto a workpiece W and performing reflow soldering using the hot air. A workpiece transport line 14 for transporting the work W is provided from the workpiece transport port 12 provided on the main body 11 to the workpiece transport port 13 provided on the other side of the apparatus main body 11.
Along the line, a preheating hot air blower 22° 32 and a reflow hot air blower 2 are placed opposite the workpiece conveyance line 14.
5.35 is provided, and this preheating hot air blower 22
．． 32 and a reflow hot air blower 25.35 is a hot air reflow device in which the distance between the hot air blower 25 and the reflow hot air blower 25 is variably adjustable.

In the invention of claim 2, the preheating hot air recovery device 23.33 for recovering the hot air blown out from the preheating hot air blower 22.32 of claim 1 is arranged on the opposite side of the workpiece loading port 12, and the reflow A reflow hot air recovery device 26.36 that recovers the hot air blown out from the hot air blowers 25 and 35.
is a hot air reflow device located on the opposite side from the workpiece exit 13.

(Function) The invention of claim 1 provides a hot air blower for preheating 22, 32.
The distance between the reflow hot air blower 25 and 35 is adjusted to account for the difference in the rate of decrease in the preheat temperature depending on the heat capacity of the workpiece, which occurs during movement of the preheated workpiece W until it is reflow heated. handle.

In the invention of claim 2, flux smoke and used hot air generated from the workpiece W during preheating and reflow are removed from the preheating hot air collectors 23, 33 and Since the hot air is collected by the reflow hot air recovery devices 26 and 36, flux smoke and hot air do not escape from the workpiece inlet 12 and workpiece outlet 13 to the outside.

(Examples) Hereinafter, the present invention will be described in detail with reference to examples shown in the drawings.

As shown in FIG. 1, a work transport for transporting a workpiece W from a workpiece loading port 12 provided on the right side of the device main body 11 to a workpiece loading port 13 provided on the left side of the device main body 11. A line 14 is provided.

This workpiece conveyance line is attached to the mounting frame 21 provided above this workpiece conveyance line 14! An upper preheating hot air blower 22 and an upper preheating hot air recovery device 23 facing the workpiece transfer line 14 are attached via a mounting plate 24, and an upper reflowing hot air blower 25 and an upper reflowing hot air blower 25 facing the workpiece conveyance line 14 are also installed. A hot air recovery device 26 is attached via a mounting plate 27.

Similarly, a lower preheating hot air blower 32 and a lower preheating hot air recovery device 33 facing the workpiece conveyance line 14 are attached to a mounting frame 31 provided below the workpiece conveyance line 14 via a mounting plate 34. At the same time, a lower reflow hot air blower 3S and a lower reflow hot air recovery device 36, which also face the workpiece conveyance line 14, are attached via a mounting plate 37.

The upper preheating hot air recovery device 23 and the lower preheating hot air recovery device 33 are connected to the upper preheating hot air blower 22.
The upper reflow hot air recovery device 26 and the lower reflow hot air recovery device 36 are provided on the opposite side of the workpiece inlet 12 with respect to the lower preheating hot air blower 32 and the lower preheating hot air blower 32.
is provided on the side opposite to the workpiece outlet 13 with respect to the upper reflow hot air blower 25 and the lower reflow hot air blower 35.

As shown in FIG. 1, each hot air blower 22°25, 3
2. 35 and each hot air collector 23.26.33.36
and a corresponding connection port 41 provided in the device main body 11 are communicated with each other through a bellows 42 . This is because the mounting plate 24.27.34.37 is movably mounted along the mounting frame 21.31, and the distance between the mounting plate 24.34 of the preheat part and the mounting plate 27.37 of the flow part is This corresponds to a structure in which the temperature is adjusted.

Like the mounting plate 34 of the lower preheat section shown in FIG. 3, each mounting plate 24.27.34.37 has an elongated hole 45. The movement of each mounting plate 24, 27, 34, 37 is adjusted by loosening the bolt 46 screwed into the mounting plate 24, 27, 34, 37.

In this way, by adjusting the distance, from the preheat area 48 formed between the upper preheating hot air blower 22 and the lower preheating hot air blower 32, the upper reflow hot air blower 25 and the lower reflow The distance to the reflow area 49 formed between the hot air blower 35 and the hot air blower 35 is variably adjusted.

As shown in FIG. 2, a pipe line 5
1. 52, the suction port 5 of the preheating blower 53
4 is connected to the upper preheating hot air blower 22 and the lower preheating hot air blower 32, and the discharge port 55 of the preheating blower 53 is connected to the branch portion 56 and the pipe line 57.
58.

Further, the suction port 64 of the upper reflow blower 63 and the suction port 66 of the lower reflow blower 65 are connected to the upper reflow hot air recovery device 26 and the lower reflow hot air recovery device 36 through pipe lines 61 and 62, respectively. , the upper reflow hot air blower 25 and the lower reflow hot air blower 35 have a discharge port 67 of the upper reflow blower 63 and a discharge port 68 of the lower reflow blower 65 connected to the conduit 69.7.
They are connected to each other via 0.

As shown in FIG. 4, the preheat hot air blower 22.32 and the reflow hot air blower 25.35 are as follows:
A blower lower 2 is provided at the center of one side of the heater box 71 , and a collision diffusion plate 74 is provided inside the blower lower 2 through a surrounding ventilation gap 73 . An electric heater 75 is disposed throughout the interior, and a perforated plate 77 having a large number of hot air jetting holes 76 is provided over the entire surface of the heater box 71 on the opposite side from the blower lower 2. This perforated plate 77
A CA thermocouple 78 is placed inside.

Then, in the preheating hot air blower 22 32 and the reflow hot air blower 25 , 35 , the air forced into the blower lower 2 of the heater box 71 is transmitted to the collision diffusion plate 74 .
The hot air collides with the air, diffuses throughout the interior of the heater box 71 through the ventilation gap 73, is uniformly heated by the electric heater 75, and is uniformly ejected toward the workpiece W from the large number of hot air ejection holes 76 in the perforated plate 77. . The temperature of the hot air blown out from this porous plate 77 is measured by the thermocouple 78,
Based on the error between the measured value and the set value, the electric heater 75
energization is controlled.

The preheat hot air recovery device 23.33 and the reflow hot air recovery device 26.36 are open ducts as shown in FIG.

Next, the operation of this embodiment will be explained.

The air discharged from the preheating blower 53 is turned into hot air by the electric heater 75 built in the upper preheating hot air blower 22 and the lower preheating hot air blower 32, and is blown onto the upper and lower surfaces of the workpiece W. Work W
Both sides are simultaneously preheated to about 150°C by hot air.

The flux smoke and used hot air generated from the workpiece W during this preheating are collected by the upper preheating hot air collector 2.
3 and the lower preheat hot air recovery device 33, and are returned to the preheat blower 53 through a filter (not shown). At this time, the preheat area 48
Since the direction of hot air movement in is opposite to the workpiece inlet 12, flux smoke and hot air do not escape from the workpiece inlet 12 to the outside.

The air discharged from the upper reflow blower 63 is turned into hot air by the electric heater 75 built in the upper reflow hot air blower 25, and is blown onto the upper surface of the workpiece W, heating the upper surface of the workpiece to about 220 to 230°C. Heat. This heating causes reflow soldering (melting of cream solder) on the upper surface of the workpiece. The used hot air is then collected by the upper reflow hot air recovery device 26 and returned to the upper reflow blower 63 through a filter (not shown). At the same time, the air discharged from the lower reflow blower 65 is turned into hot air by the electric heater 75 built in the lower reflow hot air blower 35, and is blown onto the lower surface of the workpiece W to bring the lower surface of the workpiece to the required reflow temperature. Heat until.

This heating allows reflow soldering (
(melting of cream solder) is done. Then, the used hot air is collected by the lower reflow hot air recovery device 36,
It is returned to the lower reflow blower 65 through a filter (not shown).

Flux smoke and used hot air generated from the workpiece W by the hot air heating in the reflow area 49 are also collected in the recovery device 26, 36 in the opposite direction to the workpiece unloading port 13. Flux smoke and hot air do not escape.

As mentioned above, in the reflow part, the upper hot air circulation system and the lower hot air circulation system are completely separated, so the air volume and heat amount of both can be controlled independently, and parts mounted on the top of the workpiece can be controlled independently. Both sides of the workpiece can be heated simultaneously with the air volume and heat amount corresponding to the heat capacity and the heat capacity of the parts mounted on the bottom surface of the workpiece. Even if cream solder with different melting points is used on the top and bottom surfaces of the work W,
Both sides can be reflow soldered at the same time.

In addition, the heat capacity of the workpiece W varies depending on the size of the printed wiring board and the heat capacity of the parts mounted on the board, and the temperature profile (workpiece temperature rise and fall characteristics) of the workpiece W also differs depending on the heat capacity of the workpiece W. Accordingly, a mounting plate 24.34 of said preheated part;
Adjust the distance between the reflow part and the mounting plate 27.37. For example, when flowing a workpiece W with a small heat capacity,
The mounting position is adjusted so that the distance is relatively small to cope with a relatively rapid drop in preheat temperature that occurs during movement of the workpiece between the preheat area 48 and the reflow area 49. In addition, when a workpiece W having a large heat capacity is to be flowed, the mounting position is adjusted so that the distance is relatively large, and the preheat area 48 and reflow area 4
This corresponds to a relatively gradual drop in preheat temperature that occurs during movement of the workpiece to and from 9.

[Effects of the Invention] According to the invention of claim 1, by adjusting the distance between the hot air blower for preheating and the hot air blower for reflow, the temperature profile of the workpiece from the preheating area to the reflowing area can be adjusted to the same temperature as that of the workpiece. Can be variably adjusted according to heat capacity.

According to the invention of claim 2, flux smoke and used hot air generated from the workpiece during preheating and reflowing are collected by the hot air recovery device in the opposite direction to the workpiece inlet and the workpiece outlet. No leakage to the outside from the delivery entrance or workpiece exit.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the hot air reflow device of the present invention, Fig. 2 is a circuit diagram of the hot air reflow device, and Fig. 3 is a plan view showing the mounting plate of the hot air blower and hot air recovery device. , FIG. 4 is a sectional view of the hot air blower. W...Workpiece, 11...Device body, 12...Workpiece inlet, 13...Workpiece outlet, 14...Workpiece transfer line, 22.32...Hot air blower for preheating, 23, 33
...Hot air recovery device for preheating, 25.35.Hot air blower for reflow, 26.36.Hot air recovery device for reflow. Strange [

Claims (2)

[Claims] (1) In a hot-air reflow device that blows hot air onto the workpiece and performs reflow soldering using this hot air, from the workpiece loading port provided on one side of the device body to the workpiece loading port provided on the other side of the device body. , a workpiece conveyance line is provided for conveying the workpiece, and along this workpiece conveyance line, a hot air blower for preheating and a hot air blower for reflow are provided opposite to the workpiece conveyance line. A hot air reflow device characterized in that the distance between the hot air blower and the hot air blower is variably adjustable. (2) A hot air recovery device for preheating that collects the hot air blown out from the hot air blower for preheating is placed on the opposite side of the workpiece entrance, and a hot air recovery device for reflowing that collects the hot air blown out from the hot air blowing device for reflowing. 2. The hot air reflow apparatus according to claim 1, wherein the recovery device is disposed on the opposite side of the workpiece exit.