JPH0585261B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vapor reflow soldering device, and particularly relates to a so-called flat pack, in which electrode terminals are taken out flatly in four directions.
This article relates to a soldering device suitable for high-density mounting using surface-mounted chip components such as ICs, resistors, and capacitors.

[Conventional technology]

In recent years, the high-density mounting of electronic components on printed wiring boards has become more and more advanced, but since the soldering process for bonding electronic components such as semiconductors and chip parts to printed wiring boards is the final process of the line, it is important to know whether the soldering is good or not. Since it affects the performance of parts,
Soldering technology has come to be seen as the most important technology on the line. Recently, due to the need to improve the uniformity of temperature distribution in the furnace where soldering work is carried out and to avoid harmful overheating of electronic components, steam with a high specific gravity relative to air has been used as a heat medium and its latent heat of condensation has been utilized. Vapor reflow soldering equipment, which heats the workpiece using a vapor reflow method, is attracting attention.

For example, as described in Japanese Patent Application Laid-Open No. 60-106502, this device mounts electronic components on the solder pattern of a printed wiring board, and places the printed wiring board in saturated steam of a heat medium having a high specific gravity relative to air, as described above. This is a soldering device equipped with a vapor tank called a vapor reflow tank, which performs soldering by passing the soldering process through the vapor reflow tank.

First, a typical conventional vapor reflow soldering apparatus using a belt conveyor will be described with reference to FIG.

In FIG. 4, the apparatus includes a steam generation tank 4, a carry-in side conveyance path 5, a carry-out side conveyance path 6, a heating heater 7, a carry-in side upper and lower coolers 8 and 10, an output side upper and lower coolers 9 and 11, Carrying-in side exhaust port 12, carrying-out side exhaust port 1
a reflow chamber 1 consisting of 3, a preheating chamber 2 consisting of a preheating heater 16, a cooling chamber 3 consisting of a cooling jacket 20, a drive system including a conveyor 17, a drive roller 21, an input roller 22, an output roller 23, etc., a valve 25, Cooler 26, pump 27, filter 28
It consists of a filtering system including

The operation of the vapor reflow soldering apparatus configured as described above will be explained.

The saturated steam 15 of the heat medium that is boiled and evaporated by the heater 7 immersed in the heat medium 14 accumulated at the bottom of the steam generation tank 4 rises to the top, and the soldering member 1
8 is heated, a part of it condenses and liquefies, falls, and accumulates at the bottom of the steam generation tank 4. The saturated steam 15 that has flowed into the carry-in side conveyance path 5 and the carry-out side conveyance path 6 is cooled and liquefied by the carry-in side upper and lower coolers 8 and 10 and the carry-out side upper and lower coolers 9 and 11, and then flows through the return pipe 19. and returns to the bottom of the steam generation tank 4. A small amount of remaining steam flows into a recovery device (not shown) through the inlet and outlet exhaust ports 12 and 13, and is liquefied and recovered. After the work is finished, the heat medium 14 accumulated at the bottom of the steam generation tank 4 passes through the piping 24 and the valve 25 and enters the cooler 26, where it is cooled and sent to the filter 28 by the pump 27. The resulting flux is separated and purified. Purified heat medium 1
4 once enters the conveyor path lower cooler 10 or 11, returns to the bottom of the steam generation tank through the pipe 19, and repeats this process to complete the filtering.

On the other hand, the soldering parts 18 heated by the preheating heater 16 and carried from the preheating chamber 2 to the reflow chamber 1 by the conveyor 17 are heated by contact with the saturated steam 15, and in the steam generation tank 4, due to the latent heat of condensation of the saturated steam 15. The solder is heated and melted, and the components are soldered together. The soldering member 18 is cooled as soon as it enters the discharge-side conveyance path 6, enters the cooling chamber 3, is further cooled by the cooling jacket 20, and is discharged from the apparatus.

[Problem that the invention seeks to solve]

In the vapor reflow soldering apparatus as described above, the following problems occur.

1. When the temperature of the heating medium in the steam generation tank gradually decreases as the purification time in the filter progresses, the flux contained in the heating medium begins to precipitate and adhere to the walls and heater surfaces. In particular, flux adhering to the heater surface acts as a thermal resistance, raising the heater surface temperature, shortening its life and reducing reliability. In addition, the frequency of cleaning increases, which lowers productivity and increases running costs, resulting in lower economic efficiency.

2. When the heat medium is in the steam generation tank, saturated steam corresponding to the temperature is generated and flows out into the conveyance path.

Therefore, the recovery device must be operated until a predetermined temperature is reached, which increases running costs and reduces economic efficiency.

3. When a heat medium is cooled with a cooler, flux precipitates depending on the temperature, so it tends to adhere to the walls of the flow paths of the cooler, pump, etc. and become clogged.

The cooling capacity of the cooler and the pumping capacity of the pump are reduced, resulting in a decrease in reliability.

An object of the present invention is primarily to provide a vapor reflow soldering device that improves the reliability of the device.

[Means for solving problems]

In order to achieve the above object, the configuration of the vapor reflow soldering apparatus according to the present invention is to generate steam that performs soldering by bringing saturated vapor of a heating medium into contact with the workpiece to heat and melt the solder on the workpiece. a filtering device for separating flux from the heat medium accumulated at the bottom of the steam generation tank and purifying the heat medium; and a flow system for circulating the heat medium between the steam generation tank and the filtering device. In the vapor reflow soldering apparatus, the heating medium flow path between the bottom of the steam generating tank and the filtering device is configured to receive the heating medium accumulated at the bottom of the steam generating tank. A container having a volume and equipped with a device for cooling the heat medium from the bottom of the steam generation tank is provided.

Further, the container is equipped with a device for removing flux separated by cooling the heat medium.

[Effect]

After the work is completed, the entire amount of the high-temperature heat medium accumulated at the bottom of the steam generation tank is put into a container equipped with a cooling device located at the bottom, so that little saturated steam is generated and flux does not adhere to the heater etc. When the heating medium is lowered to a predetermined temperature in the vessel, flux precipitates, but since these fluxes are removed by the removal device, the precipitated flux is not sucked into the pump, improving the reliability and economy of the device. improves.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described in detail using FIGS. 1 to 3.

FIG. 1 shows an embodiment of the present invention, which includes a preheating chamber, a reflow chamber, and a cooling chamber, has a cooling device in the filtering system, and is equipped with a container having a volume capable of containing the entire amount of the heat medium.

The apparatus is the same as the filtering system of the conventional apparatus except that a container 29 having a cooling device 30 and an easy-to-clean structure is provided instead of the heat exchanger.

After the work is completed, filtering is performed in batches, and when the heat medium 14 at the bottom of the steam generation tank 4 reaches a predetermined temperature, the valve 25 opens and the heat medium 14 passes through the pipe 24 and accumulates in the container 29. Heat medium 14
is lowered to a predetermined temperature by the cooling device 30.
When the temperature of the heating medium 14 decreases, the flux contained in the heating medium 14 begins to precipitate, so the pump 27 sends the heating medium 14 to the filter 28, where the flux is separated and purified, and then transferred to the lower part of the conveyance path. It is returned to the steam generation tank 4 through the coolers 10, 11 or directly.

FIG. 2 shows an embodiment of the present invention in which the container shown in FIG. 1 is provided with a flux remover having a wire mesh attached to the bottom thereof.

The heat medium 14 accumulated in the container 29 is transferred to the cooling device 30
When the heating medium 14 is cooled, the flux contained in the heating medium 14 precipitates and collects in the upper part. When the pump 27 starts to send the heat medium 14 to the filter 28, the liquid level of the heat medium 14 in the container 29 starts to drop, so a flux remover 31 with a wire mesh or the like installed at the bottom of the container 29 is used to remove the flux. Flux can be removed.

FIG. 3 shows another embodiment of the present invention, which is equipped with a container having a flux removing device in which a scraping plate operates instead of the wire mesh shown in FIG.

When the heat medium 14 is cooled by the cooling device 30, the flux contained in the heat medium 14 is precipitated and collected in the upper part, so that the motor 32 and the belt 3
3, the flux can be collected and removed by the scraping plate 34 that moves from side to side.

According to the above configuration, the following effects are achieved.

1. Since the heat medium in the steam generation tank is transferred from the steam generation tank to the lower container in a high temperature state, the flux contained in the heat medium does not precipitate and adhere to the heater. Therefore, the life of the heater is extended, and the period for cleaning is longer, reducing running costs and improving economic efficiency.

2. Since the heat medium in the steam generation tank is extracted at high temperature into the lower container, less saturated steam is generated from the steam generation tank after the operation is stopped, and the time the recovery device is in operation is short, making it highly economical. .

3. Even when the power is lost due to a power outage, the heat medium in the steam generation tank is extracted into the lower container, so there is less saturated steam flowing into the conveyance path, and there is no leakage outside the equipment, resulting in high safety for workers.

4. Since the container is equipped with a cooling device and a flux remover, flux deposited during cooling is removed and does not adhere to pumps, piping, valves, etc., improving reliability.

〔Effect of the invention〕

According to the present invention, since the entire amount of the heat medium in the steam generation tank is placed in a high-temperature state in a container equipped with a cooling device, flux that precipitates as the temperature of the heat medium decreases does not adhere to the heater, pump, piping, etc. equipment reliability is improved. Furthermore, since less saturated steam flows from the steam generation tank to the conveyance path, the operating time of the recovery device is shortened, improving economic efficiency.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a vapor reflow soldering apparatus according to an embodiment of the present invention, and FIG.
3 and 3 are cross-sectional views showing other embodiments of the device of the present invention, and FIG. 4 is a typical conventional vapor reflow soldering device. 1...Reflow room, 2...Preheating room, 3...Cooling room, 4...Steam generation tank, 5...Carry-in side conveyance path, 6
...Export side conveyance path, 7...Heater, 14...
Heat medium, 15... Saturated steam, 17... Conveyor,
18...Soldering member, 27...Pump, 28
... Filter, 29 ... Container, 30 ... Cooling device, 31 ... Flux remover, 34 ... Scraping plate.

Claims (1)

[Scope of Claims] 1. A steam generation tank that performs soldering by bringing saturated steam of a heat medium into contact with the workpiece to heat and melt the solder of the workpiece, and the heat accumulated at the bottom of the steam generation tank. In the vapor reflow soldering apparatus, the vapor reflow soldering apparatus includes a filtering device that separates flux from the medium and purifies the heat medium, and a flow path that circulates the heat medium between the steam generation tank and the filtering device, The heat medium flow path between the bottom of the steam generation tank and the filtering device has a volume sufficient to receive the heat medium accumulated at the bottom of the steam generation tank, and the heat transfer path from the bottom of the steam generation tank is provided. A vapor reflow soldering device characterized by having a container equipped with a device for cooling a medium. 2. The vapor reflow soldering apparatus according to claim 1, wherein the container is equipped with a device for removing flux separated by cooling the heat medium. 3. The vapor reflow soldering apparatus according to claim 1, wherein the heat medium circulation channel is equipped with a pump for circulating the heat medium.