JPH01305594A - Reflow soldering method and its device - Google Patents

Abstract

PURPOSE:To prevent the worsening of work environment by smoke and poisonous gas by returning smoke-cleared and deodorized air in a heating room through a piping part after the smoke and the poisonous gas which are produced in the heating room at the time of a reflow treatment are allowed to act on a catalyst to clear. CONSTITUTION:Air heated by a heater 11, smoke and poisonous gas produced from flux and the like are made to flow as shown by the arrow B in each flow passage 14, 15, 16 and further flowed in a burning device 20 through a sending-out pipe as shown by the arrow C. On the other hand, when a catalyst 23 is touched on the catalyst which is heated at the higher temperature than the melting temperature of solder paste 3 by a heater 21 and a temperature regulator 22, the smoke is oxidized and resolved to burn, oxygen is heated air is consumed and the poisonous gas is deodorized. Thus, the smoke is cleared in a catalyst device 20 by the above burning and the deodorized and heated air of low oxygen content is sent to each blower 13 through a supply pipe 25 from the device as shown by the arrow D.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention provides a reflow soldering method that includes a combustion device that removes smoke such as flux and odor gas generated when solder paste melts during reflow processing. and equipment.

[Conventional technology]

Conventionally used reflow soldering equipment temporarily attaches chip components to a printed circuit board using a solder base 1 or adhesive, and then solders them by irradiating air heated to 215°C or higher or far infrared rays. Soldering was performed by melting the paste, and after the soldering was completed, it was allowed to cool naturally and solidify, thereby attaching the chip components to the printed circuit board.

In addition, in the preheating room and reflow room, in order to heat the solder paste, air blown by a blower fan is heated by a heater, and after melting the solder paste and performing soldering in this heated atmosphere, the solder paste is heated. The air flows back to the respective blower fans through flow passages formed in the heating chamber and reflow chamber.

[Invention or problem to be solved]

By the way, in the conventional reflow soldering equipment as described above, when the solder paste is melted with heated air, the flux, etc. contained in the solder paste is heated and generates smoke and odoriferous residue, and this flux, etc. The smoke and odorous residue flow together with the heated air through the flow path to the blower fan, and then returned to the preheating chamber and reflow chamber. Therefore, there is a problem in that a large amount of smoke adheres to the printed circuit board, inner wall surface, heater, blower fan, exhaust fan, exhaust duct, etc. in the preheating chamber and reflow chamber.

In addition, some of the smoke and odor gas are discharged to the outside of the reflow soldering apparatus, which poses problems such as deterioration of the working environment and generation of pollution.

This invention was made to solve the above-mentioned problems, and the smoke and odor gas such as flux generated by heated solder paste is further heated and removed by the combustion action caused by the reaction of a catalyst. The object of the present invention is to provide a reflow soldering method and device that reuses the heat generated.

(Means for Solving Problem i!!!) The reflow soldering method according to the first aspect of the present invention is characterized in that a combustion device is provided to remove smoke and odor residue generated during reflow processing in a heating chamber. After the deodorized heated air is removed by acting on the catalyst, the heated air that has been de-smoked and deodorized is returned to the heating chamber through the piping section.

Further, the reflow soldering apparatus according to the second aspect of the present invention is provided with a combustion device equipped with a catalyst that removes smoke and odor gas generated in the heating chamber, and heats the combustion device via a piping section. It is connected to the room.

[Effect]

The reflow soldering method and apparatus according to the present invention bring smoke and odor gas generated by heating the solder paste in a heating chamber into contact with a catalyst in a combustion device, and the combustion effect caused by the reaction causes smoke and odor gas to be brought into contact with each other. Removes odor gas. The heated air that has been smoked and deodorized is returned from the combustion device to the heating chamber via the piping section.

〔Example〕

The drawing is a side sectional view showing an embodiment of the present invention. In this figure, 1 is a printed circuit board, 2 is a chip component, 3 is a solder paste, and 4 is the entire reflow soldering device. Reference numeral 5 denotes a belt conveyor as a means for conveying the printed circuit board 1, and a mesh-like belt conveyor made of metal is used. 6.7 is an inlet and an outlet for the printed circuit board 1;
8.9 is a primary heating chamber for the solder paste 3;
In the second heating room, the outer walls 8a, 9a and the inner wall 8b,
9b is formed. 10 is a reflow chamber in which the printed circuit board 1 is soldered, and has an outer wall 10a and an inner wall 10b.
is formed. A plurality of heaters 11 are used, such as sheathed heat or far infrared heaters, and each heater 11 controls the atmosphere in the primary heating chamber B, the secondary heating chamber 9, and the reflow chamber 10. is set so that the temperature gradually increases from the loading port 6 to the loading lower direction (in the direction of arrow A) with a required temperature difference. Reference numeral 118 denotes a shielding plate for preventing the printed circuit board 1 and the chip components 2 from being directly irradiated with the radiant heat generated from each of the heaters 11 . Reference numeral 12 denotes a partition plate that maintains the air heated by the heat generated from the adjacent heaters 11.11 at a required temperature difference, and is provided between the heaters 11.11. 13 is a blower fan; 14, 15, and 16 are flow paths through which the air heated in the primary heating chamber 8, the secondary heating chamber 9, and the reflow chamber 10 flows, which heats the soldering paste 3; Smoke and odorous gases such as flux generated by this process also flow.

17 is a cooling fan, 1B is an exhaust fan, and 19 is an exhaust duct.

The preheating chambers 8 and 9 and the reflow chamber 10 are vertically symmetrical with respect to the belt conveyor 5.

Reference numeral 20 denotes a combustion device for removing the smoke and odorous residue, which includes a heater 21 for heating a catalyst 23 (to be described later), and a temperature controller for heating the smoke and odorous gas to control the optimal reaction (combustion) temperature to about 250°C. A container 22 is provided, in which heated smoke and odorous scum are brought into contact with the inside of a wire mesh stretched over the frame to oxidize and decompose and burn granular materials such as platinum-alumina. A catalyst 23 is housed there. Reference numeral 24 denotes a delivery pipe 25 for sending heated air, smoke, and odor gas from inside each of the flow passages 14, 15, and 16 to the combustion device 20, respectively;
is a supply pipe for supplying the heated air that has been desmoked and deodorized by the combustion device 20 to each blower fan 13. On the other hand, although not shown in the drawings, flow paths are provided for flowing from each flow path 14, 15, 16 to each blower fan 13, and a damper (
(not shown) is provided.

In the reflow soldering apparatus 4 configured as described above, the air blown by each blower fan 13 flows between each partition plate 12 as shown by arrow B, and flows from the carry-in port 6 toward the carry-out lower. Heating is performed by a heater 11 that is set to sequentially increase the temperature with a required temperature difference.

For this reason, the temperature of the heated τ surrounding air is close to room temperature near the loading port 6, and increases almost linearly from the primary heating chamber 8 to the secondary heating chamber 9. Then, the temperature becomes about 215° C., and the solder paste 3 melts.

Therefore, the printed circuit board 1 carried in through the loading port 6 travels in the direction of arrow A toward the primary heating chamber 8 and the secondary heating chamber 9, thereby causing the solder paste 3 to reach the required temperature difference. Since the solder paste 3 is heated successively to a high temperature, smoke such as flux and odor gas are generated.

Smoke and odorous gas generated from the air heated by the heater 11 and flux etc. flow through each flow path 14, 15, 16 as shown by arrow B, and further into a delivery pipe as shown by arrow C. 24 into the combustion device 20. On the other hand, the catalyst 23 is heated by the heater 21 and the temperature regulator 22 to a temperature higher than the melting temperature of the solder paste 3, which is 2158°C. Then, the smoke and odor gas 2 are removed from the heated catalyst 23.
When it comes into contact with the gas, the smoke oxidizes and decomposes and burns, consuming the oxygen in the heated air and deodorizing the odorous gas. Therefore, by this combustion, heated air with a low oxygen content, which is smoke-free and deodorized in the catalyst device 20, passes from the catalyst device 20 to each blower fan 13 through the supply pipe 25 as shown by the arrow. Sent.

The temperature of the heated air supplied from the combustion device 21 to each blower fan 13 is adjusted through the flow passages 14.1'5. By adjusting the opening and closing of a damper (not shown) in 16, outside air is taken in, mixed, adjusted and circulated, and excess heated air is exhausted to the outside via an exhaust fan 18 and an exhaust duct 19.

(Effects of the Invention) As explained above, the reflow soldering method of the present invention removes smoke and odor gas generated during reflow processing in a heating chamber by acting on a catalyst provided in a combustion device. Since the heated air that has been de-smoked and deodorized is returned to the heating chamber through the piping, smoke such as flux and odorous gases generated by heating are burned and removed, and then passed through the reflow soldering equipment. This reduces the amount of smoke adhering to printed circuit boards, inner walls, heaters, blower fans, exhaust fans, ducts, etc., which improves the deterioration of the working environment caused by smoke and odorous gases, and helps prevent pollution. has advantages.

Further, the reflow soldering apparatus of the present invention is provided with a combustion device equipped with a catalyst for removing smoke and odor gas generated in the heating chamber, and the combustion device is connected to the heating chamber via a piping section. By providing a simple combustion device, it is possible to remove smoke and odorous gases generated from flux, etc., and it has advantages such as improving the working environment and reducing the cost of pollution prevention, making it economical.

In addition, since the air heated by the combustion of flux smoke is used again for reflow soldering, the oxidation of the solder paste is reduced due to the reduced oxygen content, resulting in printed circuit boards with good soldering properties. has.

[Brief explanation of the drawing]

The drawing is a side sectional view showing an embodiment of the present invention. In the figure, 1 is a printed circuit board, 2 is a chip component, 3 is a solder paste, 4 is a reflow soldering device, 8 is a primary heating chamber, 9 is a secondary heating chamber, 10 is a reflow chamber, 1
1 is a heater, 13 is a blower fan, 14, 15, 16 is a flow path, 18 is an exhaust fan, 19 is an exhaust duct, 20 is a combustion device, 21 is a heater, 22 is a temperature regulator, 23 is a catalyst, 24 is a delivery The tube 25 is a supply tube.

Claims (2)

[Claims] (1) In a reflow soldering method in which a printed circuit board is placed on a transfer device and soldered in a heating chamber while being transported, smoke and odor gas generated during the reflow process are burned in the heating chamber. A reflow soldering method characterized in that the heated air, which has been removed by acting on a catalyst provided in the apparatus, is removed and smoked and deodorized is then returned into the heating chamber through a piping section. (2) In a reflow soldering device equipped with a transport device for placing and transporting a printed circuit board and a heating chamber for soldering the printed circuit board, smoke and odor gas generated in the heating chamber are removed. A combustion device equipped with a catalyst is provided,
A reflow soldering apparatus characterized in that the combustion device is connected to the heating chamber via a piping section.