JPH05337677A - Chamber for soldering and formation of its atmosphere - Google Patents

Abstract

PURPOSE:To enable the formation of the atmosphere of an extremely low oxygen concn. in a short time even if an inert gas is not excessively supplied into a chamber body. CONSTITUTION:The chamber body 36 is internally delineated and formed by many partition plates to preheating zones 41, 42, 43, reflow zones 44, 45 and a cooling zone 46. An alcohol tank 62 housing isopropyl alcohol 61 is provided on the outside of the chamber body 36. A pipeline 63 led out of the tank 62 is internally provided with a pump 64 for controlling the supply rate of the alcohol to the inside of the chamber body according to the oxygen concn. in the chamber body. The pipeline 63 is connected to nozzles 65 mounted to the upper parts of the respective zones of the chamber body 36. The oxygen concn. in the chamber body decreases when the alcohol sprayed and gasified from the nozzles 65 into the chamber body 36 and the residual oxygen in the chamber body are brought into a vigorous reaction by a heater 66 for combustion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering chamber used in a reflow type or flow type (jet type) automatic soldering apparatus for soldering in an inert atmosphere and a method for forming an atmosphere thereof. is there.

[0002]

2. Description of the Related Art For example, a jet type automatic soldering apparatus is
As shown in FIG. 4, along the conveyor 11 that conveys the work (substrate) W to be soldered, the nozzle unit 12 of the spray fluxer for flux application, the surplus flux collecting unit 13 facing the nozzle unit 12, and the work W are prepared. A preheater 14 for heating and a solder bath 17 having a primary jet nozzle 15 and a secondary jet nozzle 16 for soldering a work W are sequentially arranged.

The preheater 14 and the jet nozzles 15 and 16
Is covered with a chamber body 18 for preventing oxidation, the inert gas flow meter 20 is controlled according to the oxygen concentration in the chamber body measured by the oxygen concentration meter 19, and the chamber body 18 is fed from the inert gas supply pipe 21. An inert gas such as nitrogen is supplied into the inside.

As described above, conventionally, an inert gas such as nitrogen is injected into the chamber body 18 which is substantially sealed, and the injection amount of the inert gas is increased until the inside of the chamber body reaches a desired low oxygen concentration. The method is adopted. The gas of the organic solvent such as the work coating flux released from the work W in the chamber body at the time of soldering and the oxygen brought into the chamber body 18 together with the work W increase the oxygen concentration in the chamber body. The increase in oxygen concentration is detected by the oxygen concentration meter 19, and the inert gas flow meter 20 is controlled so as to increase the amount of inert gas supplied.

[0005]

As described above, conventionally, since the increase in the oxygen concentration is prevented by increasing the supply flow rate of the inert gas, the running cost of the inert gas is large, which is not preferable. In other words, until now, a large flow rate of inert gas was needed to dilute and discharge residual oxygen, and it took a considerable amount of time for the effects of diluting and discharging oxygen to appear, making concentration control difficult. It was

The present invention has been made in view of the above circumstances, and it is possible to form an atmosphere having an extremely low oxygen concentration in a short time without excessively supplying an inert gas into the chamber body. It is intended.

[0007]

According to a first aspect of the present invention, in a soldering chamber in which an inert gas is supplied into a chamber body and soldering is performed in a low oxygen concentration atmosphere, a flammable fluid is added to the chamber. A combustible fluid supply unit that supplies the main body, a combustible fluid control unit that controls the supply amount of the combustible fluid into the chamber body according to the oxygen concentration in the chamber body, and a combustible fluid disposed in the chamber body. It is a soldering chamber provided with an oxidation reaction part for combining a fluid and residual oxygen in the chamber body.

According to a second aspect of the present invention, in the soldering chamber according to the first aspect, the inside of the chamber main body is divided into a plurality of zones along the work transfer path, and the boundaries between the zones are the work pieces. This is a soldering chamber in which the oxidation reaction part is arranged also in the part facing the transport path.

According to the third aspect of the invention, only the inert gas is injected into the chamber main body while the supply of the flammable fluid into the chamber main body is stopped so that a rapid oxidation reaction does not occur at the initial stage of operation, After the oxygen concentration in the chamber body is reduced to a certain level by the inert gas, a combustible fluid is supplied into the chamber body, and the oxidizing reaction section provided in the chamber body separates the combustible fluid and residual oxygen in the chamber body. This is a method for forming an atmosphere in a soldering chamber in which the oxygen concentration in the chamber body is further reduced by combining them.

[0010]

According to the first aspect of the present invention, the combustible fluid is supplied into the chamber body, and at the same time the combustible fluid and the residual oxygen in the chamber body are combined by the oxidation reaction section in the chamber body to consume the residual oxygen. By doing so, the oxygen concentration in the chamber body is lowered. If the oxygen concentration in the chamber body rises, the supply amount of flammable fluid increases, and the chamber body is continuously burned by burning flammable gas such as flux solvent applied to the workpiece. If the internal oxygen concentration is sufficiently low, the input of the combustible fluid is reduced or stopped.

According to a second aspect of the present invention, the oxidation reaction part provided between the zones in the chamber main body at the boundary portion where the atmosphere movement is concentrated provides an oxidation reaction between the combustible fluid moving between the zones and oxygen. Oxygen transfer between zones is prevented by encouraging.

According to the third aspect of the invention, only the inert gas is injected into the chamber body at the initial stage of operation, and after the oxygen concentration in the chamber body is reduced to a certain concentration by the inert gas, a rapid explosion or the like occurs. Since there is no risk of oxidation reaction, a flammable fluid is supplied into the chamber body, and the flammable fluid and residual oxygen in the chamber body are combined by the oxidation reaction section to further reduce the oxygen concentration in the chamber body.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in FIGS.

FIG. 1 shows a reflow type soldering apparatus using a nitrogen atmosphere. An endless conveyor 32 for transferring a work (substrate) W is provided in the apparatus main body 31.
An inlet throat 35, a chamber body 36, and an outlet throat 37 are provided in series between the work loading unit 33 and the work unloading unit 34. Entrance throat 35 and exit throat 37
Is an inert gas (such as nitrogen gas) supplied from an inert gas supply source (not shown) into the chamber main body 36 through the pipe 38.
To suppress the leakage from the inside of the chamber body.

Inside the chamber main body 36, a net conveyor 40 for collecting the falling work is provided below the work transfer conveyor 32, and this work transfer conveyor is further provided.
The first preheat zone 41, the second preheat zone 42, the third preheat zone 43, the first reflow zone 44, the second reflow zone 45, and the cooling zone are provided by a large number of partition plates provided so as to avoid the 32 and the net conveyor 40. 46
Are formed along the work transfer path. Further, the oxidation reaction chambers 47 are arranged at the boundaries between the zones.

An atmosphere stirring fan 52 driven by a motor 51 is provided in each zone 41 to 46 of the chamber body 36, and an atmosphere temperature control heater 53 is provided in each heating zone 41 to 45. Further, a cooling coil 54 is provided in the cooling zone 46. The heater 53 for controlling the ambient temperature in the heating zones 41 to 45 is controlled to have a surface temperature of about 400 ° C.

A flammable fluid supply unit (alcohol tank) 62 for supplying a flammable fluid (isopropyl alcohol, etc.) 61 to each zone 41 to 46 in the chamber body 36 is provided outside the chamber body 36. A combustible fluid control unit (pump or solenoid valve) 64 that controls the supply of the combustible fluid 61 into the chamber body according to the oxygen concentration in the chamber body is provided in the pipe 63 drawn from the oxidative fluid supply unit 62. The conduit 63 is provided and connected to a nozzle 65 attached to the upper part of each zone of the chamber body 36.

In each of the zones 41 to 46 in the chamber main body 36, an oxidation reaction section 66 for combining the combustible fluid with the residual oxygen in the chamber main body is provided at a position where the work W is not so affected by heat. ing. As the oxidation reaction section 66,
A combustion heater (nichrome wire heater, etc.) whose surface temperature is controlled to about 700 ° C, or the temperature inside the chamber body (100 ° C
Use a catalyst such as platinum, nickel, copper, etc., which is kept at ~ 300 ° C. When used as a catalyst, it may not be energized.

Further, the oxidation reaction chamber 47 arranged at the boundary between the zones 41 to 46 is also provided with an oxidation reaction section (combustion heater or catalyst) 67 at a portion facing the work transfer path.

FIG. 2 is an enlarged view of a part of the chamber main body 36. The oxidation reaction part (combustion heater or catalyst) 66 does not affect the work W so much as to generate an internal atmosphere gas. It is vertically attached to the partition plate 71 so as to be easily contacted. A sampling gas extraction pipe 72 is drawn out from the upper part of the chamber main body 36, and an oxygen concentration meter 73 is connected to the end of the pipe 72, and the flammable fluid control unit (pump Alternatively, a control circuit 74 for driving the solenoid valve) 64 is connected.

Next, the operation of the embodiment shown in FIG. 1 will be described mainly with reference to FIG.

In the initial stage of operation, only an inert gas such as nitrogen (N ₂ ) gas is supplied to the chamber body 36 while the supply of the combustible fluid into the chamber body 36 is stopped so that a rapid oxidation reaction does not occur.
Inject into 36. Since most of the air in the chamber body 36 is replaced by this inert gas, reflow soldering can be performed in a low oxygen concentration high temperature atmosphere whose temperature is controlled by the atmosphere stirring fan 52 and the atmosphere temperature control heater 53. Done.

Since there is no fear of a rapid oxidation reaction after the oxygen concentration in the chamber body is lowered to a certain concentration by the inert gas, the flammable fluid control unit (pump or solenoid valve) 64 is operated to cause the nozzle 65 to operate. A flammable fluid (isopropyl alcohol) is intermittently sprayed or instilled into the chamber body 36.

The alcohol (boiling point 80 ° C.) is vaporized by the preheat temperature or the reflow temperature in the chamber main body and undergoes a phase change to the flammable gas 61a not only in the case of intermittent spraying but also in the case of drip injection. The flammable gas 61a and the residual oxygen in the chamber body are oxidized by the oxidation reaction section 66 provided inside, and the oxygen concentration in the chamber body further decreases. That is, the combustible gas 61a supplied into the chamber body 36 and the residual oxygen in the chamber body are combined (combusted) by the oxidation reaction section 66 in the chamber body.
By consuming the residual oxygen, it is possible to reduce the oxygen concentration in the chamber body to a region that is difficult to achieve with only the inert gas in a short time.

When the oxidation reaction section 66 is a combustion heater, the oxidation reaction section 66 has the effect of burning the flux gas to reduce the contamination in the chamber body 36.

The control circuit 74 controls the combustible fluid control unit 64 so that the amount of spray or drip increases when the oxygen concentration in the chamber body is high, and the spray of the combustible fluid 61 is performed when the oxygen concentration is low. The flammable fluid control unit 64 is controlled so that the amount or drip amount is reduced or becomes zero. That is, if the oxygen concentration in the chamber body increases, the supply of the flammable fluid 61 is increased, and the work W is introduced into the chamber body 36 one after another and the flammability generated from the flux solvent applied to the work W is increased. If the oxygen concentration in the chamber body is sufficiently lowered by the combustion of the gas, the supply of the combustible fluid 61 is reduced or stopped.

In this way, the flammable gas 61 in the chamber body is
Since the residual oxygen in the chamber body is reduced by the oxidation reaction of a, an inert gas for forming the atmosphere (nitrogen gas, etc.)
It is sufficient if the purity and flow rate are sufficient to reduce the oxygen concentration to a level where there is no danger of explosion even if the internal concentration of the flammable gas 61a rises. Purity does not require large amounts of inert gas.

The oxidation reaction portion 67 provided at the boundary portion where the atmosphere movement is concentrated between the zones in the chamber main body 36, by promoting the oxidation reaction between the combustible gas and the oxygen moving between the zones 41 to 46. , Control the oxygen concentration for each zone.

FIG. 3 shows an example in which the present invention is applied to a flow type soldering apparatus. Instead of the atmosphere temperature control heater 53, a jet type solder bath 81 is provided below the work transfer conveyor 32.
And the molten solder 83 jetted from its nozzle 82.
Except that the work W is soldered by
Since it is the same as the embodiment shown in FIG. 2, the same reference numerals as those in FIG.

The combustible fluid supply means and the oxidation reaction section 66 according to the present invention are provided at least in the first reflow zone.
Must be provided on 44.

As the flammable fluid 61, a flammable liquid (alcohol, etc.) that changes its phase into a flammable gas when heated is used. It may be done.

[0032]

According to the first aspect of the present invention, even if a large amount of high-purity inert gas is not supplied into the chamber body, the atmosphere having an extremely low oxygen concentration can be shortened by the oxidation reaction. Can be formed in time. Therefore, the inert gas may be a relatively low-purity gas, for example, the low-purity inert gas supplied from a small-sized nitrogen generator or the like without supplying liquid nitrogen or the like from a large tank can be used for the oxidation reaction. Since a soldering atmosphere having a low oxygen concentration can be formed in the chamber body, the running cost required to supply the inert gas can be significantly improved. Moreover, by utilizing this oxidation reaction, the oxygen concentration in the chamber body can be lowered at an early timing.

According to the second aspect of the present invention, the oxidation reaction portion provided in the boundary portion between the zones in the chamber body where the gas movement is concentrated promotes the oxidation reaction to move between the zones. Since oxygen can be removed, it is possible to control the oxygen concentration for each zone.

According to the third aspect of the invention, only the inert gas is injected into the chamber body while the supply of the combustible fluid into the chamber body is stopped at the beginning of the operation, and the inside of the chamber is kept at a low oxygen content. After the concentration is reached, a combustible fluid is supplied into the chamber body to remove the residual oxygen in the chamber body by an oxidation reaction, so the risk of explosion due to a rapid oxidation reaction can be prevented, and safety can be ensured. ..

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example in which a soldering chamber of the present invention is applied to a reflow type soldering device.

FIG. 2 is an enlarged sectional view showing a part of the reflow soldering device of the above.

FIG. 3 is a cross-sectional view showing an example in which the soldering chamber of the present invention is applied to a jet type soldering device.

FIG. 4 is a sectional view showing a usage example of a conventional soldering chamber.

[Explanation of symbols]

 36 Chamber body 41 to 46 Zone 61 Flammable fluid 62 Flammable fluid supply section 64 Flammable fluid control section 66 Oxidation reaction section 67 Oxidation reaction section

Claims (3)

[Claims] 1. An inert gas is supplied into the chamber body,
In a soldering chamber where soldering is performed in a low oxygen concentration atmosphere, a combustible fluid supply unit that supplies a combustible fluid into the chamber body, and a combustible fluid that flows into the chamber body depending on the oxygen concentration in the chamber body A soldering chamber comprising: a flammable fluid control unit that controls a supply amount; and an oxidation reaction unit that is disposed in the chamber body to combine the flammable fluid and residual oxygen in the chamber body. 2. The chamber main body is divided into a plurality of zones along the work transfer path, and the oxidation reaction section is also arranged at the boundary between the zones and facing the work transfer path. The chamber for soldering according to claim 1. 3. In the initial stage of operation, only the inert gas is injected into the chamber body while the supply of the combustible fluid into the chamber body is stopped so that a rapid oxidation reaction does not occur, and the chamber body is filled with the inert gas. After the oxygen concentration has dropped to a certain level, a combustible fluid is supplied into the chamber body, and the oxidizing reaction part provided in the chamber body combines the combustible fluid and residual oxygen in the chamber body to generate oxygen in the chamber body. A method for forming an atmosphere in a soldering chamber, which further reduces the concentration.