JPH06196242A - Reflow soldering device - Google Patents

Abstract

PURPOSE:To prevent the re-sticking of solder flux to a printed board or a device by providing a ultraviolet ray radiation chamber in a reflow zone, and sucking and decomposing the heated and evaporated solder flux via a duct. CONSTITUTION:A printed board is conveyed in the arrow direction, it is heated in a preheat zone 1 by a panel heater or hot air, it is kept at the constant temperature in a uniform heating zone 2, and solder is fused in a reflow zone 3 and solidified in a cooling zone 4. The solder flux evaporated from the printed board in the zone 3 is sucked from a duct 5 and guided into a ultraviolet ray radiation chamber 7 installed with ultraviolet lamps 6. The chemical bond of the composition of the flux is cut off by ultraviolet rays mainly having the wavelengths of 185nm and 254nm, and it is reacted with the generated ozone and changed into carbon dioxide and steam. The atmosphere after decomposition is returned into a furnace or discharged to the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow soldering device for soldering electronic parts to a printed circuit board.

[0002]

2. Description of the Related Art An outline of a general reflow soldering apparatus is shown in FIG. The printed circuit board is conveyed in the direction of the arrow and heated to a certain temperature in the preheat zone 1 by the panel heater and hot air, and then the uniform heating zone 2
After being kept at a constant temperature in, the solder is melted in the reflow zone 3 and finally the solder is solidified in the cooling zone 4.

Flux is applied to the printed circuit board for the purpose of improving the adhesion of solder, improving lubricity, and preventing oxidation. This flux mainly evaporates in the reflow zone 3, but is condensed and deposited in the next low temperature portion such as the cooling zone 4 and the partition wall between the cooling zone 4 and the reflow zone 3 and then dripped to the printed circuit board after soldering. Adhesion and contamination occur. A sufficient mechanism for preventing such reattachment of the solder flux to the printed circuit board is not yet known.

There is also a method of discharging a large amount of the atmosphere in the furnace containing solder flux vapor to the outside of the apparatus as one of the measures, but it is a good measure because it adversely affects the stability of the temperature in the furnace and causes environmental pollution. I can't say.

An object of the present invention is to solve the above problems and to provide a reflow soldering apparatus in which reattachment of solder flux is reduced.

[0006]

SUMMARY OF THE INVENTION The present invention is a reflow soldering apparatus that applies solder to a printed circuit board, mounts electronic components on the printed circuit board, and then heats and solders the printed circuit board. It is characterized in that the solder flux is decomposed by introducing it into a room in which a lamp is provided and irradiating the solder flux in a gaseous state with ultraviolet rays.

The ultraviolet lamp used here is 185n
It radiates ultraviolet rays with wavelengths mainly of m and 254 nm, and these ultraviolet rays break the chemical bonds of organic substances and at the same time change to gaseous substances by the action of ozone, or form a new surface layer.

[0008]

[Function] Since the solder flux is decomposed by ultraviolet rays, it is possible to prevent the solder flux from reattaching to the printed circuit board or the reflow soldering device.

[0009]

EXAMPLES The present invention will be described below with reference to examples. FIG. 1 is a sectional view of a reflow soldering apparatus according to the present invention. The solder flux evaporated from the printed board is sucked from the duct 5 and guided into the ultraviolet irradiation chamber 7 in which the ultraviolet lamp 6 is installed. Here, the solder flux is 185n.
The chemical bond in the solder flux composition is broken by ultraviolet rays with wavelengths mainly at m and 254 nm, and at the same time, it reacts with ozone that is generated and changes into carbon dioxide and water vapor. The atmosphere after the solder flux is decomposed in this way is returned to the furnace or discharged to the outside.

[0010]

As described above, the reflow soldering apparatus of the present invention prevents the reattachment of the solder flux to the printed circuit board or the reflow soldering apparatus by decomposing the solder flux in the furnace by the action of ultraviolet rays. be able to.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a reflow soldering device according to the present invention.

FIG. 2 is a schematic sectional view of a general reflow soldering device.

[Explanation of symbols]

 1 Pre-heat zone 2 Uniform heating zone 3 Reflow zone 4 Cooling zone 5 Duct 6 UV lamp 7 UV irradiation chamber

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[Procedure amendment]

[Submission date] December 16, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

Claims (2)

[Claims] 1. A reflow soldering apparatus for applying solder to a printed circuit board, mounting electronic components, and then heating and soldering, an ultraviolet irradiation chamber provided with a lamp for generating ultraviolet rays, and a solder flux evaporated during heating. And a suction mechanism for sucking into the inside of the ultraviolet irradiation chamber to introduce the reflow soldering device. 2. The reflow soldering device according to claim 1, wherein the ultraviolet lamp is a low-pressure mercury lamp which emits ultraviolet rays having wavelengths of 185 nm and 254 nm.