JPH077260A - Automatically soldering apparatus - Google Patents

Abstract

PURPOSE:To largely reduce inert gas consumption without deteriorating soldering performance by detecting inert gas concentration in a heating chamber, and supplying both the external air and inert gas to the chamber while controlling both the air and the gas in response to the concentration. CONSTITUTION:The oxygen concentration in a reflow soldering chamber RF is detected by an inert gas concentration sensor 2. When the oxygen concentration is 500ppm or more, the opening of a valve contained in an electropneumatic regulator 29 is controlled according to an electric signal from a nitrogen gas controller 24. When the oxygen concentration is 500ppm or less, the air is supplied to the chamber RF. Thus, since the oxygen concentration in the chamber RF is controlled to the 500ppm by supplying not only the nitrogen gas but also the air, a much larger amount of gas can be supplied as compared with the case where only the nitrogen gas is supplied, and hence the pressure in an automatically soldering apparatus 1 can be held considerably higher than the atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic soldering device, and more particularly to only external air or external air and an inert gas in a heating chamber of an automatic soldering device for soldering in an atmosphere filled with an inert gas. Both of them are supplied while controlling the flow rate thereof, the inert gas concentration in the heating chamber is suppressed to the necessary minimum concentration, and the heating chamber is kept at a high pressure to keep the inert gas of low concentration from the automatic soldering device. Preventing unscheduled air from entering from the outside by letting gas flow out, greatly reducing the consumption of inert gas, and even if the environment near the automatic soldering device changes suddenly. The present invention relates to an epoch-making automatic soldering device capable of performing reliable soldering while keeping a constant inert gas concentration in the automatic soldering device.

[0002]

2. Description of the Related Art Conventionally, in an automatic soldering apparatus, an electronic component is soldered to a substrate by melting the solder by raising the temperature of the substrate and the solder to a high temperature in an atmosphere containing a large amount of oxygen. According to the automatic soldering device, the soldering part and the molten solder are oxidized when the solder and electronic parts are exposed to oxygen at high temperature, and it is not possible to secure sufficient soldering performance, It had the disadvantage of having to do some work.

In particular, as electronic components have become smaller in recent years and the lead wires have become thinner accordingly, even a slight defect such as oxidation of a soldered portion has serious consequences such as deterioration of reliability of electronic products. It was the cause.

In order to solve such a drawback, the automatic soldering apparatus is filled with an inert gas such as nitrogen gas to perform soldering in a state where oxygen is blocked, and the electronic parts, the substrate and the solder are heated to a high temperature. In addition, an automatic soldering device has been proposed in which soldering is performed so that a soldering portion and molten solder are not oxidized.

Since the inert gas such as nitrogen gas used in this type of automatic soldering device is expensive, it is necessary to minimize the leakage of the inert gas from the automatic soldering device. Various measures have been taken to increase the tightness of the device.

However, a board to be soldered must be carried into the automatic soldering apparatus from the outside of the apparatus, and must be carried out from the apparatus to the outside. In the conventional automatic soldering apparatus, the board is carried in. Moreover, it is almost impossible to prevent the leakage of the inert gas from the carry-in port and the carry-out port for carrying out, and a large amount of the inert gas leaks out of the apparatus, which is very uneconomical. there were.

That is, the temperature is controlled so that the temperature gradually increases from the preheating chamber to the reflow soldering chamber. For example, in a reflow soldering apparatus, the gas density is thin in the high temperature portion and the temperature is low in the low temperature portion. Since the gas density becomes high, the inert gas causes a flow from the low temperature portion having high gas density to the high temperature portion having low gas density.

In this case, due to the flow of the inert gas due to the temperature difference, the inert gas flows out from the carry-out port and the expensive inert gas is consumed.

Further, in such a case, with the outflow of the inert gas from the carry-out port, air flows into the automatic soldering apparatus from the carry-in port to reduce the inert gas density in the preheating chamber. However, the effect of preventing oxidation will be reduced.

A fan for circulating hot air for melting the solder is provided in the preheating chamber, the reflow soldering chamber, etc., and the inert gas in the chamber is circulated to generate a high temperature inert gas. The board is sprayed and heated from above to perform preheating and heating for soldering, but the inert gas hitting the board is shunted to the front and rear sides in the direction of travel of the board, and the inert gas flows out in the direction described above. In either case, a large amount of inert gas was exhausted unnecessarily by further promoting the above or causing a flow in the opposite direction.

As a method for preventing the inflow of air from the carry-in port, there has been proposed a device for supplying more inert gas than that flowing out of the carry-out port to increase the internal pressure in the automatic soldering device. However, this device has a drawback that it requires an extremely large amount of inert gas and is not economical.

Further, in the above method, in order to minimize the consumption of the inert gas, the amount of the inert gas ejected is limited to such an extent that a very small amount of the inert gas flows out from the carry-in port for economic reasons. Inevitably, if there is a sudden environmental change such as wind blown outside the automatic soldering equipment, it will not be able to cope with this and external air will flow in from the carry-in port or carry-out port, affecting the soldering performance. However, there is a drawback that it is difficult to deal with sudden changes such as accidents.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the above-mentioned drawbacks of the prior art. The purpose of the present invention is to detect the inert gas concentration in the heating chamber and It is necessary to solder the inert gas concentration in the heating chamber by either supplying only the external air while controlling it according to the active gas concentration, or by supplying both the external air and the inert gas to the heating chamber while controlling both. Is to be maintained at a minimum concentration, and thereby the consumption of the inert gas is significantly reduced without deteriorating the soldering performance.

Another object of the present invention is to allow the pressure in the heating chamber to always be maintained at atmospheric pressure or higher without increasing the consumption of the inert gas by the above-mentioned structure, and thereby to realize the automatic soldering apparatus. Even if there is a sudden environmental change such as blowing out of the automatic soldering equipment by constantly flowing out the inert gas from the loading and unloading port of the board, the external air directly flows in from the loading or unloading port. To prevent
It is to ensure stable soldering performance.

[0015]

SUMMARY OF THE INVENTION In summary, the present invention (Claim 1) relates to an automatic soldering device for heating and soldering a substrate on which electronic components are mounted while being transported in a heating chamber filled with an inert gas, An inert gas concentration sensor for detecting an inert gas concentration in the heating chamber, and an air supply device for controlling the amount of external air according to a detection control signal from the inert gas concentration sensor to supply the heating chamber. And is configured to control the inert gas concentration in the heating chamber to a predetermined concentration. Further, the present invention (Claim 2) is an automatic soldering device for heating and soldering a substrate on which an electronic component is mounted in a heating chamber filled with an inert gas while heating and soldering the substrate. An inert gas concentration sensor for detecting, an inert gas supply device for controlling the supply amount of the inert gas according to a detection control signal from the inert gas concentration sensor and supplying the inert gas to the heating chamber, and the inert gas. An air supply device for controlling the amount of external air according to a detection control signal from a gas concentration sensor and supplying the air to the heating chamber, and configured to control the inert gas concentration in the heating chamber to a predetermined concentration. It is characterized by having done.

The present invention (claim 3) is an automatic soldering device for heating and soldering a substrate on which electronic parts are mounted while being transported in a heating chamber filled with an inert gas.
An inert gas concentration sensor for detecting an inert gas concentration in the heating chamber, and an inert gas concentration sensor for controlling the supply amount of the inert gas according to a detection control signal from the inert gas concentration sensor to supply the inert gas to the heating chamber. An active gas supply device and an air supply device for controlling the amount of external air according to a detection control signal from the inert gas concentration sensor and supplying the air to the heating chamber are provided, and the inert gas concentration in the heating chamber is controlled. Controlling to a predetermined concentration and keeping the pressure in the automatic soldering device at atmospheric pressure or higher so that the inert gas is always flown out from the carry-in port and the carry-out port of the substrate of the automatic soldering device. It is characterized by being configured.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings. 1 and 2, an automatic soldering device 1 according to the present invention includes an inert gas concentration sensor 2, an inert gas supply device 3, and an air supply device 4.

An example in which the present invention is applied to a reflow type automatic soldering apparatus 1 which is an example of an automatic soldering apparatus will be described with reference to FIG. First, the basic configuration of the reflow-type automatic soldering apparatus 1 will be described. The housing 6 of the reflow-type automatic soldering apparatus 1 is divided into preheating chambers PH ₁ and PH ₂ , a reflow soldering chamber RF, and a slow cooling chamber C by partition walls 8.
The heating chamber 9 divided into L is formed, and the structure of each chamber is substantially the same except that the internal temperature is different.

The preheating chambers PH ₁ and PH ₂ , the reflow soldering chamber RF and the slow cooling chamber CL are provided with a well-known endless chain conveyor 10 as an example of a conveying device so as to penetrate through them. A substrate (not shown) carried in at the station 11 is conveyed leftward in the drawing to preheat chambers PH ₁ and PH ₂ , a reflow soldering chamber RF, and a slow cooling chamber C.
It is configured to be sequentially conveyed to the L and carried out to the carry-out station 13.

A casing (not shown) is provided in each of the preheating chambers PH ₁ and PH ₂ , the reflow soldering chamber RF and the slow cooling chamber CL which are independently filled with an inert gas such as nitrogen gas. An ascending circulation passage is formed between the heating chamber 9 and the outer wall of the heating chamber 9 (on the back side of the drawing), and a descending circulation passage is formed in the casing.

Above the chain conveyor 10 in the casing, there is provided a heating device 18 having a sandwich structure in which an electric heater is sandwiched between metal plates having a large number of holes, and a preheating chamber PH ₁ The heating is controlled so that the inside is about 190 ° C., the inside of the preheating chamber PH ₂ is about 150 ° C., the inside of the reflow soldering chamber RF is about 250 ° C., and the inside of the slow cooling chamber CL is about 130 ° C. Has become.

The substrates loaded on the chain conveyor 10 are preheated in the preheating chambers PH ₁ and PH ₂ while being conveyed, and then rapidly heated to the soldering temperature in the reflow soldering chamber RF to be soldered. It is designed to be gradually cooled in the slow cooling chamber CL and carried out from the carry-out station 13.

The blower 19 is for forcibly circulating the heated inert gas such as nitrogen gas filled in the heating chamber 9, and the preheating chambers PH ₁ , PH ₂ , reflow soldering chamber RF and A belt is provided between a pulley 22 fixed to a shaft 21 supported by a bearing 20 such as a ball bearing in a centrifugal blower such as a sirocco fan or the like, which is disposed in the lower part of the slow cooling chamber CL, and a pulley of a motor (not shown) ( (Not shown) is wound around and is driven by the motor.

Then, after the nitrogen gas filled in the heating chamber 9 is sucked and heated by the heating device 18, it is lowered in the descending circulation passage to heat the substrate conveyed by the chain conveyor 10 and then pressure-fed by the blower 19. However, it is configured to be raised again and circulated through the rising circulation passage.

The substrate is gradually heated to the soldering temperature by the heated nitrogen gas to solder the electronic component to the substrate.

The inert gas concentration sensor 2 is for detecting the nitrogen gas concentration which is an example of the inert gas in the heating chamber 9, especially in the reflow soldering chamber RF which has the greatest effect on the soldering performance. The pipe 23 communicates with the reflow soldering chamber RF, and the reflow soldering chamber RF is connected.
The nitrogen gas therein is guided to the inert gas concentration sensor 2 to detect the nitrogen gas concentration.

The inert gas concentration sensor 2 is connected to a nitrogen gas control device 24 and an air control device 25, which are electronic circuits for performing PID control in response to a detection signal from the inert gas concentration sensor 2, by an electric wire 27. The nitrogen gas control device 2 is electrically connected and converts the concentration of nitrogen gas into an electric quantity such as current or voltage proportional to the concentration and outputs a detection signal.
4 and the air control device 25.

The inert gas supply device 3 is for supplying an inert gas such as nitrogen gas. In this embodiment, the gas cylinder 26 containing liquid nitrogen and the vaporizer 2 are used.
8, an electropneumatic regulator 29, a flow control valve 30 and a supply pipe 31. Liquid nitrogen in the gas cylinder 26 is introduced into the vaporizer 28 by the supply pipe 31 to be vaporized into nitrogen gas, and then the electropneumatic regulator. The flow rate is controlled by 29 and the flow rate control valve 30, and is supplied to the reflow soldering chamber RF via the supply pipe 31.

The air supply device 4 includes a reflow soldering chamber R.
It is for supplying external air into F, and is composed of a compressor 32, an electropneumatic regulator 33, a flow control valve 34, and a supply pipe 35. After the external air is compressed by the compressor 32, Empty regulator 33
The flow rate control valve 34 controls the flow rate of the compressed air and supplies the compressed air to the reflow soldering chamber RF via the supply pipe 35.

The present invention is configured as described above,
The operation will be described below. 2 and 3, first, at the carry-in port 36 of the carry-in station 11,
When the substrates are loaded on the chain conveyor 10, the substrates are conveyed to the left in the figure, and are rapidly heated in the preheating chamber PH ₁ where nitrogen gas is heated to about 190 ° C., which is a relatively small electronic component with a small heat capacity. Is immediately heated to about 190 ° C, which is the same as the temperature of nitrogen gas, but for relatively large electronic components with large heat capacity, the surface is heated to about 190 ° C, but the inside is not sufficiently heated. The temperature is lower.

Next, the temperature of the electronic parts having a small heat capacity is lowered, and the temperature of the electronic parts having a large heat capacity is gradually transferred to the preheating chamber PH ₂ heated to about 150 ° C. to adjust the whole temperature. Then, all the components of the substrate and the electronic components reach a uniform temperature of about 150 ° C., and the preheating is completed.

The nitrogen gas that comes into contact with the substrate from above branches in the left-right direction and flows. The direction of the flow is determined by the positional relationship between the substrate and the blower 19, and the position of the substrate being conveyed always changes. Therefore, the flow direction also changes from the right direction to the left direction and from the left direction to the right direction. For example, in the preheating chamber PH ₁ , the nitrogen gas flows in the first prechamber 39 or in the preheating chamber 39. It flows toward the room PH ₂ .

The nitrogen gas that has passed through the chain conveyor 10 and further descended is sucked by the blower 19, flows to the left and right, rises in the ascending circulation passage, and returns to above the heating device 18.

At this time, the temperature of the nitrogen gas is detected by a temperature sensor (not shown) and transmitted to a control device (not shown), and the electric power supplied to the heating device 18 is adjusted by the command of the control device to heat the heating device 18. The nitrogen gas in the chamber 9 is controlled to have a predetermined temperature.

Next, the substrate is transferred to the reflow soldering chamber RF, where it is heated in contact with the nitrogen gas heated to about 250 ° C. in the same manner as in the preheating chambers PH ₁ and PH ₂ , so that the cream solder is applied. Melts and the electronic component is soldered to a predetermined portion of the substrate.

Since the preheating chambers PH ₁ and PH ₂ and the reflow soldering chamber RF are filled with nitrogen gas whose gas concentration is controlled to be extremely low as about 500 ppm as described later, The molten solder and the lead wires of the electronic component are not oxidized, and ideal soldering is performed.

The substrate which has been soldered in the reflow soldering chamber RF and is still in a high temperature state is further conveyed to the slow cooling chamber CL at a temperature of about 130 ° C. and slowly cooled, and then conveyed to the carry-out station 13. , And is carried out from the carry-out port 38.

The electronic parts are soldered to the substrate as described above, and as a result of investigating and studying for a long time the effect of changing the oxygen concentration in the heating chamber 9 on the soldering performance, it is about 500 ppm or less. If so, the soldering performance showed almost no change, and it was found that there was no practical problem.

The oxygen concentration in the heating chamber 9 is simply 500 ppm.
If it is only about the degree, only the nitrogen gas is heated in the heating chamber 9
It is also possible to supply it to the heating chamber 9, but according to this method, the supply amount of the nitrogen gas is not so large, and therefore the heating chamber 9
The internal pressure also becomes almost the same as the external pressure, and if there is a sudden environmental change such as blowing of air outside the automatic soldering device 1, the outside air will flow directly into the automatic soldering device 1. Therefore, it is not possible to change the nitrogen gas concentration and perform stable soldering.

In addition, the outside air is directly connected to the automatic soldering apparatus 1
In order to increase the pressure in the heating chamber 9 to the extent that it does not flow into the inside, it is necessary to supply a very large amount of nitrogen gas and always make it flow out from the carry-in port 36 and the carry-out port 38 in the directions of arrows N and O. Therefore, although the oxygen concentration in the heating chamber 9 is reduced, the oxygen concentration becomes unnecessarily low, resulting in extremely wasteful consumption of expensive nitrogen gas.

This is the main point of the present invention, and the operation thereof will be described with reference to FIG. 3. First, the inert gas concentration in the reflow soldering chamber RF in the direction of arrow A is measured by the pipe 23. the leading sensor 2, the inert gas concentration sensor 2 in step S ₁ for detecting the oxygen concentration in the reflow soldering chamber RF.

Then, in step S ₂ , the oxygen concentration is adjusted to 500
It is determined whether it is less than or equal to ppm, and if it is more than or equal to 500 ppm, the process proceeds to step S ₃ , and the detection signal is sent to the electric wire 27.
To the nitrogen gas control device 24 (direction of arrow B), and an electric signal from the nitrogen gas control device 24 (arrow C).
Direction) to control the opening degree of the valve built in the electropneumatic regulator 29.

On the other hand, the liquid nitrogen in the gas cylinder 26 is supplied to the vaporizer 28 in the direction of the arrow D and vaporized to become nitrogen gas.

The pressure of the nitrogen gas supplied to the electropneumatic regulator 29 in the direction of arrow E is adjusted by the valve built in the electropneumatic regulator 29, and then the flow rate is controlled by the flow rate control valve 30 to be supplied. It is supplied to the reflow soldering chamber RF by the pipe 31 in the direction of arrow G, and the oxygen concentration in the reflow soldering chamber RF is reduced.

In step S ₂ , the oxygen concentration is 500 ppm.
If it is determined that the following is true, the process proceeds to step S ₄ , and the detection signal of the inert gas concentration sensor 2 is transmitted to the air control device 25 via the electric wire 27 (direction of arrow H), and the air control device 25 outputs the signal. The opening degree of the valve built in the electropneumatic regulator 33 is controlled by the electric signal (direction of arrow I).

Then, after the pressure of the external air sucked in the direction of arrow J by the compressor 32 and supplied in the direction of arrow K is adjusted by the electropneumatic regulator 33, the flow rate is further controlled by the flow rate control valve 34 and the supply pipe. It is supplied to the reflow soldering chamber RF in the direction of arrow M by 35, and the oxygen concentration in the reflow soldering chamber RF is increased to 500 ppm.

As described above, the oxygen concentration in the reflow soldering chamber RF is controlled to 500 ppm by supplying not only nitrogen gas but also external air. Therefore, the oxygen concentration is much larger than that in the case of supplying only nitrogen gas. Gas can be supplied, so that the pressure in the automatic soldering device 1 can be maintained at a pressure considerably higher than the outside air.

Further, since the gas in the automatic soldering device 1 is constantly flown out from the carry-in port 36 and the carry-out port 38 in the directions of the arrows N and O, there may be a sudden situation such as wind blowing on the automatic soldering device 1. Even if it occurs, it has no effect on the gas concentration in the automatic soldering apparatus 1, and stable soldering can be performed.

In the above embodiments, the present invention has been described as being applied to a reflow automatic soldering device, but the present invention is not limited to the use in a reflow automatic soldering device. Of course, it can be applied to a dip-type automatic soldering device.

[0050]

As described above, the present invention detects the concentration of the inert gas in the heating chamber and supplies only the external air while controlling only the external air according to the concentration of the inert gas, or the external air and the inert gas. Since both of them are supplied to the heating chamber while being controlled, there is an effect that the inert gas concentration in the heating chamber can be maintained at the minimum concentration required for soldering, and as a result, the soldering performance is deteriorated. The epoch-making effect that the consumption of the inert gas can be greatly reduced is obtained.

Further, the above-mentioned structure has an effect that the pressure in the heating chamber can be always maintained at the atmospheric pressure or higher without increasing the consumption amount of the inert gas, and as a result, from the carry-in port and the carry-out port of the substrate of the automatic soldering apparatus. Even if there is a sudden environmental change such as the flow of inert gas to the outside and the wind blows outside the automatic soldering device, it is possible to prevent external air from directly flowing in from the carry-in port or carry-out port, which is stable. This has the effect of ensuring soldering performance.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the overall configuration of an automatic soldering device.

FIG. 2 is a vertical sectional view showing an operating state of the automatic soldering device.

FIG. 3 is a flowchart showing an operation routine of the automatic soldering device.

[Explanation of reference numerals] 1 automatic soldering device 2 inert gas concentration sensor 3 inert gas supply device 4 air supply device 9 heating chamber 36 substrate loading port 38 substrate loading port

Claims (3)

[Claims] 1. An automatic soldering device for heating and soldering a substrate on which electronic components are mounted while being transported in a heating chamber filled with an inert gas, the inert gas detecting an inert gas concentration in the heating chamber. A concentration sensor, and an air supply device that controls the amount of external air according to a detection control signal from the inert gas concentration sensor and supplies the air to the heating chamber,
An automatic soldering device, characterized in that the inert gas concentration in the heating chamber is controlled to a predetermined concentration. 2. An automatic soldering device for heating and soldering a substrate on which electronic components are mounted while being transported in a heating chamber filled with an inert gas, the inert gas detecting an inert gas concentration in the heating chamber. A concentration sensor, an inert gas supply device for controlling the supply amount of the inert gas according to a detection control signal from the inert gas concentration sensor to supply the heating chamber to the heating chamber, and an inert gas concentration sensor. An air supply device for controlling the amount of external air according to a detection control signal and supplying the air to the heating chamber, and being configured to control the inert gas concentration in the heating chamber to a predetermined concentration. Automatic soldering device. 3. An automatic soldering device for heating and soldering a substrate on which electronic parts are mounted while being transported in a heating chamber filled with an inert gas, the inert gas detecting an inert gas concentration in the heating chamber. A concentration sensor, an inert gas supply device for controlling the supply amount of the inert gas according to a detection control signal from the inert gas concentration sensor to supply the heating chamber to the heating chamber, and an inert gas concentration sensor. An air supply device for controlling the amount of external air according to a detection control signal and supplying the air to the heating chamber, and controlling the inert gas concentration in the heating chamber to a predetermined concentration and in the automatic soldering device. An automatic soldering device, characterized in that the pressure is maintained at atmospheric pressure or more and the inert gas is always discharged to the outside through a carry-in port and a carry-out port of the substrate of the automatic soldering device.