JP3257049B2 - Reflow device and reflow method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow apparatus, and more particularly, to a reflow apparatus and a reflow method capable of selectively performing nitrogen reflow and air reflow.

[0002]

2. Description of the Related Art After a chip is mounted on a substrate by a chip mounter or the like, the substrate is sent to a heating chamber of a reflow device.
The electrodes of the chip are soldered to the electrodes of the substrate by heating and melting the solder and then cooling and solidifying the solder.

[0003] The reflow device supplies air to the heating chamber as an inert gas in order to prevent oxidation of metal parts such as circuit patterns of the substrate, and an air reflow device for heating air in the heating chamber with a heater. And a nitrogen reflow device for heating a nitrogen gas with a heater. Conventionally, the air reflow device and the Chisso reflow device were separate devices. In recent years, however, a reflow device capable of performing both air reflow and Chisso reflow by adding a nitrogen gas supply means to the air reflow device has been proposed. Next, a conventional reflow apparatus will be described.

FIG. 3 is a side view showing the inside of the reflow device. Inside the heating chamber 100, a conveyor 103 for transporting the substrate 10 on which the chip 9 is mounted from the inlet 101 to the outlet 102 is provided. Above the conveyor 103, a heater 104 and a fan 105 are provided. . 1
Reference numeral 06 denotes a driving motor for the conveyor 103, and reference numeral 107 denotes a driving motor for the fan 105. Inlet 101 and outlet 1
02 is provided with a shutter 110 for preventing external air from flowing into the heating chamber 100. By driving the cylinder 111 to move the shutter 110 up and down, the inlet 101 and the outlet 102 are connected. Open and close. The inside of the heating chamber 100 is divided by a partition wall 112 into a preheating zone T1 on the entrance 101 side, a soaking zone T2 in the center, and a reflow zone T3 on the exit 3 side.
2, T3, a nitrogen gas supply unit 113 such as a liquid nitrogen cylinder in which liquid nitrogen is stored, a nitrogen gas generator for separating nitrogen from oxygen in the air and generating nitrogen gas.
, A nitrogen gas is supplied through a pipe 114.
115 is a valve.

Next, the operation will be described. When performing Chisso reflow, the inlet 101 and the outlet 102 are
And close the valve 115 to open the heating chamber 100.
A nitrogen gas is supplied, and the inside of the heating chamber 100 is filled with the nitrogen gas. Now, the substrate 10 on which the chip 9 is mounted is transported rightward by the conveyor 103. Meanwhile, substrate 1
At 0, the nitrogen gas heated by the heater 104 is the fan 1
05, and the substrate 10 is heated. FIG.
The solid line A indicates the temperature profile in the heating chamber 100 during the reflow of nitrogen. As shown, in general,
In the preheating zone T1, the substrate 10 is heated from normal temperature to 150 ° C.
° C, and then in the soaking zone T2,
It is heated to about 70 ° C., and then heated to 220 ° C. or more in the reflow zone T3. The melting temperature of the solder 14 is about 183 ° C., and when the substrate 10 is rapidly heated to about 223 ° C., the solder 14 is melted.

Next, when air reflow is performed, the inlet 10
1 and the shutter 110 of the outlet 102 are opened, and the valve 115 is closed to stop the supply of nitrogen gas to the heating chamber 100. Then, the inside of the heating chamber 100 is filled with air, and in this state, soldering is performed while the substrate 10 is conveyed by the conveyor 103 as in the case of the Chisso reflow.

FIG. 4 shows a chain line B in the heating chamber 1 during air reflow.
00 shows a temperature profile of 00. As shown, the temperature profile B of air reflow is higher than the temperature profile of nitrogen reflow. The reason is as follows. In the Chisso reflow, the heating chamber 100
A considerable amount of nitrogen gas is supplied to the inside at all times or almost always. However, since this nitrogen gas has a low temperature (normal temperature), heat is lost to heat the nitrogen gas to the above-mentioned temperature. On the other hand, in the air reflow, external air only flows in little by little from the inlet 101 and the outlet 102. That is, the amount of air flowing into the heating chamber 1 during the air reflow is considerably smaller than the amount of the nitrogen gas supplied to the heating chamber 100 during the nitrogen reflow. As a result, the temperature profile B of the air reflow is higher than the temperature profile of the nitrogen reflow. That is.

[0008]

In the reflow apparatus, if the actual temperature profile deviates from the ideal temperature profile, the quality of the solder deteriorates due to insufficient heating or excessive heating of the solder. Therefore, temperature control means such as a heater must be strictly controlled in order to approach an ideal temperature profile. However, in the above-described conventional reflow apparatus, since the temperature profiles change in the Chisso reflow and the air reflow, each temperature control is performed separately. And it is very difficult to control the operation of the equipment.This is one of the main reasons that the reflow equipment that can use both air reflow and chisso reflow is not widely used. Had become.

Accordingly, an object of the present invention is to provide a reflow apparatus and a reflow method capable of easily matching the temperature profiles of air reflow and nitrogen reflow.

[0010]

To this end, the present invention provides a blower for positively supplying air to the heating chamber.
A switching means for switching between the supply of nitrogen gas from the nitrogen gas supply unit and the supply of air from the blower is provided in an air supply line communicating from the nitrogen gas supply unit and the blower to the heating chamber, and the air blower is driven by driving the blower during air reflow.
It is intended to be sent to .

[0011]

[Action] Oite to the above structure, the heating at the time of nitrogen reflow
Reflow is performed while supplying nitrogen gas to the chamber. During et <br/> Arifuro Although performed by supplying actively drives the blower air to the heating chamber, in this case, the temperature and the specific heat of the air and Chissogasu is substantially the same, therefore the air reflow and nitrogen If similar temperature management is performed by reflow, a similar temperature profile will be obtained.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a side view showing the inside of the reflow device. Inside the heating chamber 1, there is provided a conveyor 4 for transporting a substrate 10 on which chips 9 are mounted from the inlet 2 to the outlet 3. Above the conveyor 4, a heater 5 and a fan 6 are provided. . 8 is a drive motor for the conveyor 4;
Reference numeral 7 denotes a motor for driving the fan 6. The inlet 2 and the outlet 3 are provided with a shutter 18 for preventing external air from flowing into the heating chamber 1.
To open and close the inlet 2 and the outlet 3 by moving the shutter 18 up and down.

The interior of the heating chamber 1 is divided by a partition wall 16 into a preheating zone T1 on the inlet 2 side, a soaking zone T2 in the center, and a reflow zone T3 on the outlet 3 side. Reference numeral 11 denotes a nitrogen gas supply unit such as a liquid nitrogen cylinder or a nitrogen gas generator that generates nitrogen gas by separating nitrogen and oxygen in the air. A nitrogen gas is supplied to a cooling chamber 20 provided at the rear of the heating chamber 1. This air supply line 14
Is provided with a flow control valve 12 and a flow meter 13. 2
Reference numeral 1 denotes a blower, which is connected to a switching valve 15 provided in the air supply line 14, and a flow regulating valve 22 and a flow meter 23 are provided in the middle thereof. By operating the switching valve 15, the supply of nitrogen gas to the heating chamber 1 by the nitrogen gas supply unit 11 and the supply of air by the blower 21 are selectively switched.

Next, the operation will be described. When performing the nitrogen reflow, the inlet 2 and the outlet 3 are closed by the shutter 18 and the valve 15 is opened to supply the heating chamber 1 with the nitrogen gas, so that the heating chamber 1 is filled with the nitrogen gas. Now, the substrate 10 on which the chips 9 are mounted is transported rightward by the conveyor 4. In the meantime, the nitrogen gas heated by the heater 5 is blown to the substrate 10 by the fan 6, and the substrate 10 is heated. Next, when performing air reflow, the shutter 18 of the inlet 2 and the outlet 3 is opened, the valve 15 is switched, the supply of nitrogen gas to the heating chamber 1 is stopped, and the blower 21 is driven to drive the heating chamber 1. While supplying air
The substrate 10 is transported by the conveyor 4 and soldered.

In this case, the flow meter 2 is set so that the supply amount of the nitrogen gas and the supply amount of the air during the nitrogen reflow are the same.
The flow rate is measured in 3 and the flow rate is adjusted by the flow rate adjusting valve 22.
If the supply amount of nitrogen gas at the time of nitrogen reflow is made equal to the supply amount of air at the time of air reflow, the temperature and specific heat of the nitrogen gas and the air are almost equal, so the temperature profile at the time of air reflow is The temperature profile is the same as when Therefore, in air reflow and chisso reflow, exactly the same temperature profile can be obtained by controlling the temperature management means such as the heater 5 and the fan 6 in exactly the same manner.

FIG. 2 shows another embodiment of the present invention.
The nitrogen gas supply unit 11 and the blower 21 have independent air supply lines 14A and 14B and valves 15A and 15B, respectively. Therefore, nitrogen gas or air is supplied to the heating chamber 1 by switching the valves 15A and 15B. Thus, various piping structures are conceivable.

[0018]

As described above , according to the present invention , an empty space is provided.
Qi and nitrogen gas are at the same temperature (normal temperature), and the specific heat is almost
Equal because, when the air reflow, by positively supplying the air <br/> air to the heating chamber by driving the blower, can obtain the same temperature profile and nitrogen reflow, thus nitrogen reflow and air reflow In any case
Also be similarly controlled temperature control means such as a heater or a fan
This gives a similar temperature profile
Thus, the temperature control means can be easily controlled.

[Brief description of the drawings]

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

FIG. 2 is a side view of a switching mechanism according to another embodiment of the present invention.

FIG. 3 is a side view of a conventional reflow device.

FIG. 4 is a temperature profile diagram of a conventional reflow device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating chamber 2 Inlet 3 Outlet 4 Conveyor 5 Heater (Temperature management means) 6 Fan (Temperature management means) 11 Nitrogen gas supply part 14 Air supply line 15 Valve (Switching means) 21 Blower

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-13474 (JP, A) JP-A-3-133198 (JP, A) JP-A-2-87557 (JP, U) (58) Investigation Field (Int.Cl. ⁷ , DB name) H05K 3/34 B23K 1/008 B23K 31/02

Claims (2)

(57) [Claims] 1. Select between Chisso reflow and air reflow
A heating chamber, a conveyor for transporting the substrate from an inlet to an outlet of the heating chamber, a heater disposed in the heating chamber for heating the substrate transported by the conveyor, and hot air flowing through the substrate. Fan, a nitrogen gas supply unit for supplying nitrogen gas to the heating chamber, a blower for supplying air to the heating chamber, and an air supply line from the nitrogen gas supply unit and the blower to the heating chamber. Switching means for switching between the supply of nitrogen gas from the nitrogen gas supply unit and the supply of air from the blower.
During air reflow, the air blower is driven to
A reflow device characterized in that it is sent to 2. A substrate is not transported in a heating chamber by a conveyor.
Then, heat the board with a heater to solder the chips.
A reflow method adapted to perform
Sometimes nitrogen gas is supplied to the heating chamber from the nitrogen gas supply unit
During air reflow, the blower is driven to
Reflow method characterized by sending air to
Law.