JP3924668B2 - Reflow device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflow apparatus for soldering electronic components or the like to a printed circuit board, for example. More specifically, the present invention relates to a reflow apparatus that can quickly discharge fumes generated during soldering to the outside of the furnace without contacting the substrate, and a reflow apparatus that can efficiently guide the discharged fumes to the processing apparatus and process them.
[0002]
In the present specification, the terms before and after refer to FIG. 1, and the left in FIG. 1 is the rear and the right is the front.
[0003]
[Prior art]
An example of a conventional reflow apparatus is shown in FIG. This reflow apparatus includes a furnace (21), a substrate transfer conveyor (22) penetrating the furnace (21) and having a substrate transfer path on the upper side, and a substrate transfer path of the conveyor (22) in the furnace (21). A plurality of fans (24) provided above, a plurality of heaters (23) disposed above the conveyor (22) in the furnace (21) and below the fan (24), and the furnace (21) The return path (29) for extracting the atmosphere of the gas and the return path (27) for supplying the extracted atmosphere to the furnace (21) again, the cooling coil (28) provided in the circulation path, and the return path (27) And a fan device (30).
[0004]
In this reflow apparatus, the atmosphere containing fumes in the furnace (21) is introduced into the forward path (29), and the fumes are tarred or condensed by the cooling coils (28), and the condensed fumes are cooled by the cooling coils ( Fume is collected by adhering to 28). The atmosphere after the fumes are collected is supplied into the furnace (21) by the return path (27).
[0005]
In the reflow apparatus shown in FIG. 3, a filter may be provided instead of the cooling coil (28).
[0006]
Furthermore, another reflow apparatus is shown in FIG. Also in this figure, the left is the rear and the right is the front.
[0007]
This reflow device comprises a furnace (31), a fume discharge pipe (32) connected to the heating section of the furnace (31), a sirocco fan (35) provided in the fume discharge pipe (32), and a fume discharge. An electric heater (33) provided in the pipe (32) and a catalyst (34) provided on the downstream side of the electric heater (33) in the fume discharge pipe (32) are provided. An air supply pipe (36) and a combustible material supply pipe (37) are connected to the discharge pipe (32). Although not shown in the figure, a transfer device for advancing the substrate (w) in the furnace (31) is provided.
[0008]
In this reflow apparatus, an atmosphere containing fumes inside the furnace (31) is extracted by a fan (35), and the fumes are oxidized by an electric heater (33) and a catalyst (34).
[0009]
[Problems to be solved by the invention]
Now, it is required to increase the mounting density of the substrate surface. For this purpose, it is necessary to reduce the size of the mounted components and to increase the wiring density by reducing the wiring dimensions, but in order to realize these, the solder area must be reduced. For this reason, it is necessary to perform soldering in a clean environment, and the degree of cleanliness in the furnace where soldering is performed is required to be, for example, about class 1000.
[0010]
However, the above two conventional reflow devices have the following problems and cannot achieve a high degree of cleanliness.
[0011]
In the conventional reflow apparatus shown in FIG. 3, when a filter is used, there is a problem that fumes are condensed and adhered to the filter, causing clogging, and cannot be used as it is.
[0012]
Further, in the case of using the cooling coil, the condensed fume is removed by adhering to the surface of the cooling coil, so that the cooling ability is reduced as the deposits are deposited, and the fumes cannot be completely removed.
[0013]
Furthermore, since the fumes collected by the filter and the cooling coil are condensed and attached to the filter and the cooling coil in a tar shape, it is difficult to remove the deposits, and the maintenance of the reflow apparatus is troublesome. is there. Further, when removing the deposits, it is necessary to stop the reflow device, so that the operation time of the device is shortened.
[0014]
Thus, in a hot air circulation reflow furnace that circulates the atmosphere in the furnace and removes fumes in the atmosphere during the circulation, high cleanliness cannot be achieved.
[0015]
In the conventional reflow apparatus shown in FIG. 4, an air flow is generated from the front and rear in the furnace (31) toward the center. Therefore, a large amount of fumes generated in the rear part of the preheating part in the furnace (31) flows from the main heating part to the preheating part, that is, from the high temperature part to the low temperature part in the furnace (31), and the cleanliness in the furnace (31) decreases. However, there is a problem that fumes may adhere to the substrate (w) and the inner wall of the furnace (31) conveyed in the furnace (31).
[0016]
An object of the present invention is to provide a reflow apparatus that can achieve a high degree of cleanliness and can be easily maintained.
[0017]
[Means for Solving the Problems and Effects of the Invention]
In order to solve the above problems, a reflow apparatus according to the present invention is a reflow apparatus for processing fumes generated from a flux component of solder in a furnace,
In a reflow apparatus including a furnace in which both front and rear ends are open, the rear end is a substrate inlet, the front end is a substrate outlet, and a preheating unit, a main heating unit, and a cooling unit are provided therein.
A heating device that radiates and heats the substrate in the furnace in the preheating section and the main heating section with an electric heater embedded in the furnace wall ;
A fume discharge pipe connected to the furnace;
Means for keeping the temperature in the fume discharge pipe above the fume condensation temperature;
A discharge means for forcibly and continuously discharging fumes generated in the furnace together with the atmosphere in the furnace into a fume discharge pipe;
A fume treatment device connected to the fume discharge pipe and continuously pyrolyzing the fumes discharged from the discharge pipe;
A fume discharge pipe is connected between the main heating unit and the cooling unit in the furnace, and discharges the atmosphere after the fume treatment to the outside while forming a flow of the atmosphere from the rear side to the front side in the furnace. It is what.
[0018]
In this reflow apparatus, the fumes are forcibly discharged from the furnace to the outside, and the atmosphere after the fumes are processed by the processing apparatus is discharged to the outside, so that the fumes are not sent again into the furnace. High cleanliness can be achieved in the furnace.
[0019]
Furthermore, in this reflow device, after the fumes are discharged from the furnace, the fume discharge pipe is kept at a temperature equal to or higher than the condensation temperature, so the fumes are not condensed in the fume discharge pipe and may clog the fume discharge pipe. Absent. Therefore, it is not necessary to perform maintenance work for removing the deposits generated by the condensation of the fumes in the fume discharge pipe, and the operation time of the apparatus becomes longer.
[0020]
In addition, since fumes are continuously and forcibly discharged from the furnace by the discharge means and processed continuously by the processing equipment, environmental pollution due to fumes is prevented and the operating time of the equipment is lengthened. Can do.
[0021]
Moreover, since the substrate is heated by a heating device embedded in the furnace wall, that is, heated without circulating hot air in the furnace, even if a small amount of fume remains in the furnace, the fumes Is not sprayed onto the substrate.
[0022]
Further, since the inner wall temperature of the fume generating portion in the furnace is higher than the fume condensation temperature, fume does not adhere to the inner wall surface of the furnace, and the furnace maintenance is easy.
[0023]
In addition, normally fumes are generated in the rear part of the preheating part and in the main heating part. Since the discharge pipe is connected between the fume generating part and the cooling part, the fumes before condensation can be efficiently discharged.
[0024]
Furthermore, since the fume discharge pipe is connected to the rear side of the fume generation part and to the front side of the cooling part, the fume does not flow back to the front side in the furnace, and the fume is brought out of the furnace before the substrate is forcibly cooled. Since it is discharged, fume does not adhere to the substrate.
[0025]
Moreover, in this reflow device, the atmosphere flows from the rear side to the front side in the furnace. Therefore, if it is applied to a normal reflow apparatus in which a preheating part is provided on the rear side in the furnace and a main heating part is provided on the front side in the furnace, the fume flows from the high temperature side to the low temperature side, that is, from the main heating part side to the preheating part side. And fume does not condense in the furnace.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
The reflow apparatus of the present invention will be described below with reference to FIGS.
[0027]
The reflow apparatus is not shown in the figure, for example, and is disposed in an outer panel made of iron plate. As shown in FIG. 1, the front and rear ends are open, the rear end is the substrate inlet (8), and the front end is A cylindrical furnace (1), which is the substrate outlet (9), a fume discharge pipe (3) with one end connected to the top of the furnace (1), and the other end of the fume discharge pipe (3) And a fume processing device (4). The processing device (4) is for processing by decomposing or burning the fume by heating, and is usually provided outside the exterior panel. Although illustration is omitted, the substrate (w) is carried into the furnace (1) from the substrate inlet (8), and the substrate (w) is advanced in the furnace (1) and the furnace ( 1) A substrate transfer device for unloading the substrate (w) is provided outside.
[0028]
The furnace (1) includes a heating unit (1c) configured by arranging a plurality of cylindrical heat insulators (1a) and (1b) in front and back, and an inlet-side cylindrical metal body connected to the rear end of the heating unit (1c). (1d) and an outlet side cylindrical metal body (1e) connected to the front end of the heating section (1c).
[0029]
An electric heater (heating device) (2) is embedded in the vicinity of the surface of the cylindrical heat insulator (1b) excluding the cylindrical heat insulator (1a) located at the front and rear ends, respectively. The side part is a preheating part, and the front part is a main heating part. Although not shown in detail, the inlet-side cylindrical metal body (1d) has an inlet purge portion, and the outlet-side cylindrical metal body (1e) has a front side of the portion where the discharge pipe (3) is connected. A cooling part and an outlet purge part are formed. The configurations of the electric heater, the exterior panel, the inlet purge unit, the cooling unit, the outlet purge unit, and the like are the same as known ones used in ordinary solder reflow furnaces. Although not shown, a supply device for supplying an atmosphere is attached to the furnace (1).
[0030]
Then, one end of the fume discharge pipe (3) is connected to a portion from the heating part (1c) in the outlet side cylindrical metal body (1e). The fume discharge pipe (3) is made of, for example, stainless steel. A sheathed heater (5) is provided over the entire outer periphery of the discharge pipe (3), and the outer periphery of the discharge pipe (3) and the heater (5) are covered with a heat insulating material (6). (3) The temperature inside is kept above the fume condensation temperature.
[0031]
In addition, a throttle part (3a) is provided in the center of the length direction of the fume discharge pipe (3), and an injector (discharge means) (7) is provided closer to the furnace (1) than the throttle part (3a). The high-pressure gas that protrudes into the fume discharge pipe (3) and blows out from the injector (7) is arranged to flow toward the processing device (4). In addition, an air supply pipe (10) is connected to the fume treatment device (4) side from the injector (7) in the fume discharge pipe (3). The injector (7) is connected to a high-pressure gas supply source (not shown).
[0032]
The fume treatment device (4) is made of a metal, for example, a stainless steel rear end closing tube (4a), a heat insulating material (4b) covering the outer periphery of the rear end closing tube (4a), and a rear end closing tube (4a). And an electric heater (4c). The electric heater (4c) is supported by a plurality of disc-like insulators (not shown) having a plurality of holes. The electric heater (4c) is connected to an appropriate power source (not shown).
[0033]
In the above reflow apparatus, pre-heat treatment, main heat treatment, and the like are performed while the substrate (w) passes through the furnace (1), and electronic components and the like are soldered to the substrate (w). Then, fumes generated from the flux component of the solder and the like are processed during soldering in the furnace (1) as follows.
[0034]
When high-pressure gas is blown from the injector (7), the flow rate of the high-pressure gas is increased at the throttle portion (3a), and the pressure at the throttle portion (3a) is reduced. Then, the atmosphere containing fumes in the furnace (1) is sucked into the fume discharge pipe (3) and sent to the fume treatment device (4). The thickness of the heat insulating material (6) covering the fume discharge pipe (3) is such a thickness that the temperature inside the fume discharge pipe (3) can be maintained at the fume condensation temperature or higher (usually 180 ° C., maximum 300 ° C.). By constantly blowing high pressure gas from the injector (7), the fumes in the furnace (1) are continuously discharged out of the furnace (1), that is, into the fume discharge pipe (3).
[0035]
The temperature inside the fume processing device (4) is always kept above the fume decomposition temperature (usually 700 ° C), and the fume sent from the discharge pipe (3) is continuously pyrolyzed to treat the processing device. It is discharged from the front end opening of (4) to the outside of the processing device (4). That is, the atmosphere exhausted from the furnace (1) and the fumes after the treatment do not return to the reflow apparatus again.
[0036]
In addition, since the electric heater (2) is embedded in the furnace wall of the heating section (1c) in the furnace (1) and the temperature of the inner wall surface of the heating section (1c) is equal to or higher than the fume condensation temperature, the inner wall surface of the heating section (1) No fume adheres to the surface.
[0037]
The fumes in the heating section (1c) are sucked into the discharge pipe (3) connected to the top of the furnace (1), so the atmosphere only rises in the heating section (1c), and the fumes are moved into the furnace (1). The substrate (w) is not lowered across the substrate (w), and no fume comes into contact with the substrate (w) regardless of the temperature in the heating section (1c).
[0038]
In the above apparatus, air may be sent into the discharge pipe (3) by the air supply pipe (10). Then, a part of the components of the fume can be burned in the processing device (4). Further, a temperature detecting means such as a thermocouple may be provided in the processing apparatus (4), and the temperature in the processing apparatus (4) may be controlled appropriately.
[0039]
Each part structure of the reflow apparatus of this invention is not restricted to said thing. For example, the furnace (1) only needs to be capable of appropriately heating the internal substrate. Furthermore, instead of the sheathed heater (5), another heater may be provided to keep the temperature in the discharge pipe (3) at or above the fume condensation temperature.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a reflow apparatus according to an embodiment of the present invention.
FIG. 2 is a partially enlarged cross-sectional view of a processing apparatus in the reflow apparatus.
FIG. 3 is a longitudinal sectional view of a conventional reflow apparatus.
FIG. 4 is a longitudinal section of another conventional reflow apparatus.
[Explanation of symbols]
(1) Furnace
(2) Heating device (electric heater)
(3) Hume discharge pipe
(4) Fume processing equipment
(5) Seed heater
(6) Insulation material
(7) Injector as discharge means
(8) Board entrance
(9) Substrate exit
(w) Board

Claims (1)

A reflow device for processing fumes generated from solder flux components in a furnace,
In a reflow apparatus including a furnace in which both front and rear ends are open, the rear end is a substrate inlet, the front end is a substrate outlet, and a preheating unit, a main heating unit, and a cooling unit are provided therein.
A heating device that radiates and heats the substrate in the furnace in the preheating section and the main heating section with an electric heater embedded in the furnace wall ;
A fume discharge pipe connected to the furnace;
Means for keeping the temperature in the fume discharge pipe above the fume condensation temperature;
A discharge means for forcibly and continuously discharging fumes generated in the furnace together with the atmosphere in the furnace into a fume discharge pipe;
A fume treatment device connected to the fume discharge pipe and continuously pyrolyzing the fumes discharged from the discharge pipe;
A fume discharge pipe is connected between the main heating unit and the cooling unit in the furnace, and discharges the atmosphere after the fume treatment to the outside while forming a flow of the atmosphere from the rear side to the front side in the furnace. Reflow device.

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