JP2002271013A - Soldering equipment and method of soldering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an equipment and method of soldering a circuit board which can prevent generation of defects without using lead-containing solder. SOLUTION: The circuit board 60 which reflowed in a reflow furnace 10 is transferred to a wave soldering bath 20. The circuit board 60 transferred to the wave soldering bath 20 is soldered with a solder wave. When soldering the circuit board 60 in the wave soldering bath 20, air is blown against the circuit board 60 from a nozzle 41 disposed above, thereby cooling the surface of the circuit board 60 on the opposite side to the wave soldering bath. By cooling the circuit board 60, the remelting of the reflowed solder is prevented, and generation of defects due to remelted of solder is prevented. Since there is no need of lowering the melting point of the molten solder in the wave soldering bath 20, soldering can be carried out without using lead-containing solder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a soldering apparatus and a soldering method, and more particularly, to a soldering apparatus and a soldering method for a circuit board.

[0002]

2. Description of the Related Art Electronic components mounted on a circuit board are fixed to the circuit board by soldering. When soldering is performed on a soldering line of a circuit board, both soldering by reflow and soldering by jet soldering are generally used. In reflow soldering, solder is printed or plated on the circuit board in advance, electronic components are mounted on the circuit board on which the solder is formed, and the circuit board is heated in a reflow furnace to melt the solder and solder. carry out. On the other hand, the soldering by the jet solder is carried out by the circuit board passing over the liquid surface of the solder that is melted and forming the jet, and is opposite to the surface on which the soldering is performed by reflow of the circuit board. Soldering is performed on the surface.

[0003]

After the reflow is performed as described above, the soldering by the jet solder is performed. Therefore, the soldering apparatus includes a reflow furnace and a jet solder bath. That is, after the reflow soldering, the soldering is performed by the jet solder.

[0004] However, when performing the soldering by the jet solder after the reflow, the reflowed circuit board passes through the liquid level of the molten solder at the time of the jet soldering. Thereby, the reflowed solder is heated by the molten high-temperature solder, and the reflowed solder is melted by heating the circuit board. For this reason, cracks and cracks may occur in the soldered portions of the electronic components mounted on the circuit board, and connection failure may occur.

It is also conceivable to lower the melting point of the solder used for the jet soldering to prevent the reflowed solder from remelting. In order to lower the melting point of the solder, it is necessary to increase the lead content in the solder. However, it is desirable to avoid the use of lead from the viewpoint of protecting the environment.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and a method for soldering a circuit board, which prevent the occurrence of defects without using lead-containing solder. Another object of the present invention is to provide a soldering apparatus and a soldering method that can be introduced at low cost and that prevent the occurrence of defects.

[0007]

According to the soldering apparatus of the first aspect of the present invention, a cooling means for cooling a surface of the circuit board opposite to the jet solder bath is provided above the jet solder bath. I have. The cooling means cools the circuit board from above the jet solder bath. By cooling the circuit board, it is possible to prevent the reflowed solder from re-melting even when the circuit board is heated during soldering by the jet solder. Further, since it is not necessary to lower the melting point of the solder in the jet solder bath, the use of solder containing lead can be avoided. Therefore, it is possible to prevent the occurrence of defects due to reheating of the reflow solder without using a solder containing lead.

According to the soldering apparatus of the present invention, the air blowing means blows air onto the circuit board when the circuit board is conveyed to the jet solder bath. For example, factories where soldering is performed often have equipment for supplying compressed air for other purposes. Therefore, the circuit board can be cooled using the air supply equipment conventionally provided in the factory without providing additional equipment. Therefore, a soldering device can be introduced at low cost. In addition, it is possible to prevent the temperature of the solder in the molten solder bath from lowering due to the injection of air at an unnecessary time.

According to the third aspect of the present invention, when the circuit board is subjected to the jet soldering, the surface of the circuit board opposite to the jet solder bath is cooled. By cooling the circuit board, it is possible to prevent the reflowed solder from re-melting even when the circuit board is heated during soldering by the jet solder. Further, since it is not necessary to lower the melting point of the solder in the jet solder bath, the use of solder containing lead can be avoided. Therefore, it is possible to prevent the occurrence of defects due to reheating of the reflow solder without using a solder containing lead.

According to the fourth aspect of the present invention, when the circuit board is subjected to the jet soldering, air is blown to the surface of the circuit board opposite to the jet solder bath. The circuit board is cooled by blowing air on the circuit board. Therefore, even when the circuit board is heated during the soldering by the jet solder, it is possible to prevent the reflowed solder from remelting. Further, since it is not necessary to lower the melting point of the solder in the jet solder bath, the use of solder containing lead can be avoided. Therefore, it is possible to prevent the occurrence of defects due to reheating of the reflow solder without using a solder containing lead.

Further, for example, in a factory where soldering is performed, equipment for supplying compressed air for other purposes is often provided. Therefore, the circuit board can be cooled at low cost by using the air supply equipment conventionally provided in the factory and without providing any additional equipment.

According to the soldering method according to the fifth aspect of the present invention, air is blown onto the circuit board when the circuit board is conveyed to the jet solder bath. Therefore, it is possible to prevent the temperature of the solder in the molten solder bath from lowering due to air injection at an unnecessary time. According to the soldering method of the present invention, the air is at room temperature. Therefore, for example, equipment for cooling air is unnecessary. Therefore, the introduction cost of equipment for cooling the circuit board does not increase.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; 1 and 2 show a soldering apparatus according to an embodiment of the present invention. As shown in FIG. 1, the soldering device 1 includes a reflow furnace 10, a jet solder bath 20, a transfer device 30, and a cooling device 40. The reflow furnace 10 is a high-temperature furnace that melts the solder printed on the circuit board 60. Solder is printed on the circuit board 60 in advance, and electronic components 61
After being mounted, it is transferred to the reflow furnace 10.

The jet solder bath 20 is provided separately from the reflow furnace 10. In the jet solder bath 20, the molten solder is jetted, and two jets 21 and 22 are formed. The circuit board 60 passes above these jets 21 and 22. Reflow furnace 10 and jet solder bath 20
A preheater 23 is provided between the two. The preheater 23 preheats the circuit board 60 transported to the jet solder bath 20.

The transfer device 30 transfers the circuit board 60 in the direction of arrow A in FIG. The transfer device 30 transfers the circuit board 60 on which the solder is printed and the electronic component 61 is mounted from the reflow furnace 10 to the jet solder bath 20. Transfer device 30
Has two rails 31 and 32 as shown in FIG. 2, and a circuit board 60 is placed between the two rails 31 and 32. The circuit board 60 is guided and transported by the two rails 31 and 32.

As shown in FIG. 1, the cooling device 40 includes an ejection part 41, an air pump 42, an air tank 43, a valve 44,
It has a detection unit 45 and a control unit 46. Spouting part 41
Is installed above the jet solder bath 20. The ejection unit 41 ejects the air supplied from the air tank 43 to the circuit board 60 transported by the transport device 30. The air pump 42 compresses the air supplied to the ejection unit 41. The air compressed by the air pump 42 is stored in the air tank 43 at room temperature. The air tank 43 and the ejection section 41 are connected by an air pipe 47, and a valve 44 is provided in the air pipe 47. The air pump 42, the air tank 43, and the air pipe 47 constitute a supply unit. The valve 44 is opened and closed by a signal from the control unit 46 to interrupt the supply of air from the air tank 43 to the ejection unit 41. The air pump 42 and the air tank 43
For example, compressed air supply equipment provided in various types of manufacturing equipment can be used.

The detecting section 45 is provided between the reflow furnace 10 and the jet solder bath 20, that is, on the inlet side of the jet solder bath 20. The detection unit 45 is installed on the same side as the ejection unit 41, that is, above the circuit board 60 transported by the transport device 30. The detection unit 45 includes, for example, a photo sensor and detects the circuit board 60 transported by the transport device 30. When detecting the circuit board 60, the detection section 45 outputs a detection signal to the control section 46.

The control unit 46 includes a detection unit 45 and a valve 4
4 is connected. When the detection unit 45 detects the circuit board 60 and outputs a detection signal from the detection unit 45, the control unit 4
6 opens the valve 44. Thus, the air is supplied from the air tank 43 to the ejection section 41, and the ejection of the air from the ejection section 41 is started. The control unit 46 closes the valve 44 when a certain time has passed since the detection signal was output from the detection unit 45.

Next, a description will be given of a soldering method using the soldering apparatus 1 having the above configuration. (1) Pre-processing stage In order to perform soldering, the circuit board 60 is pre-processed. The pre-processing performed on the circuit board 60 is performed as follows. After the through holes are formed on the circuit board 60, pads for mounting circuit patterns and surface mount components are formed. Further, paste-like solder is printed on the pads formed on the circuit board 60. For example, a through hole is formed in the circuit board 60,
After a predetermined circuit pattern and a pad are formed by etching a copper film or the like, a paste solder is formed by printing or the like. When the solder and the flux are printed, the surface mount component is mounted on a predetermined portion. The surface mount components are mounted on pads formed on the circuit board 60.

(2) Reflow Step The circuit board 60 on which the surface mount components have been assembled is transported to the reflow furnace 10. The reflow furnace 10 is maintained at a predetermined temperature. Therefore, in the reflow furnace 10, the circuit board 60 is heated to a temperature at which the solder printed on the circuit board 60 melts. When the circuit board 60 is heated in the reflow furnace 10, the solder printed on the circuit board 60 is melted, and the surface-mounted component is soldered by the melted solder.

(3) Transport Stage The circuit board 60 that has passed through the reflow furnace 10 is carried out of the reflow furnace 10. The surface mount components are fixed to the circuit board 60 carried out of the reflow furnace 10. The lead components are mounted on the unloaded circuit board 60. The lead component is mounted on the circuit board 60 by inserting a lead wire provided in the lead component into a through hole. The circuit board 60 on which the lead components are mounted is transferred by the transfer device 30 to the jet solder bath 20. When transported to the jet solder bath 20, the surface of the circuit board 60 on the side of the jet solder bath 20 is preheated by the preheater 23 in order to efficiently perform soldering in the subsequent jet soldering stage. Preheating by the preheater 23 is performed at a temperature at which the solder soldered by reflow does not melt.

(4) Jet Soldering Step After passing through the preheater 23, the circuit board 60 is transferred to the jet solder bath 20. In the jet solder bath 20, the melted solder is jetted to form jets 21 and 22.
As the circuit board 60 passes through the liquid surfaces of the jets 21 and 22, molten solder is applied to the surface of the circuit board 60 on the side of the jet solder bath 20, and soldering is performed.

In the jet soldering stage, air is jetted from the opposite side of the jet solder bath 20 to the circuit board 60 as shown in FIG. A detection unit 45 is provided at the entrance side of the jet solder bath 20.
Are provided, and when the circuit board 60 passes through the detection unit 45, a detection signal is output from the detection unit 45 to the control unit 46. When the output detection signal is input to the control unit 46,
The control unit 46 controls the valve 44 at the same time as the detection signal is input or after a certain period of time has elapsed after the detection signal is input.
To release. When the valve 44 is opened, the room temperature air stored in the air tank 43 is supplied to the ejection section 41. The air supplied to the ejection section 41 is ejected to the circuit board 60. That is, when the circuit board 60 passes above the jet solder bath 20, air is jetted from the jetting portion 41 to the circuit board 60.

The surface of the circuit board 60 opposite to the jet solder bath 20 is cooled by the air jetted from the jetting portion 41. By injecting air onto the surface of the circuit board 60 opposite to the jet solder bath 20, the maximum temperature of the circuit board 60 decreases as shown in FIG. FIG. 3 shows a change in the temperature of the circuit board 60, comparing the present embodiment in which air is injected to the circuit board 60 with a conventional example in which air is not injected. FIG. 3 shows an example in which the measurement is started at a certain time before the circuit board 60 is carried into the jet solder bath 20 and the temperature change until the circuit board 60 exits the jet solder bath 20 is periodically measured. is there.

The control section 46 counts a period from when the detection signal output from the detection section 45 is input. Then, when a predetermined period elapses, the control unit 46 closes the valve 44, and the injection of air from the ejection unit 41 is stopped. The predetermined period is set based on a speed at which the circuit board 60 is transported by the transport device 30. The predetermined period can be freely set, and the set predetermined period is controlled by the control unit 46.
Is recorded in a recording unit (not shown). For example, the circuit board 6
When the circuit board 60 reaches the jet solder bath 20 several seconds after 0 passes through the detection unit 45, the jetting of air from the jet unit 41 starts. When ejected, the ejection section 41
Can be set to end the injection of the air from the. That is, when the circuit board 60 passes above the jet solder bath 20, it can be set so that air is jetted from the jetting portion 41 to the circuit board 60.

By freely setting the period during which the air is injected from the jetting part 41, air can be jetted during a period necessary for cooling the circuit board 60, and the jet solder bath 20 is jetted by unnecessary air. A decrease in the temperature of the molten solder is prevented. When the soldering by the jet solder bath 20 is completed,
The circuit board 60 is carried out of the jet solder bath 20 by the transfer device 30, and the soldering process is completed.

As described above, according to the soldering method using the soldering apparatus 1 of the present embodiment, when performing the soldering by the jet solder, the surface of the circuit board 60 on the side opposite to the jet solder bath 20. Is cooled by air.
Therefore, when soldering with the jet solder, the circuit board 6
The temperature of 0 is reduced, preventing the reflowed solder from melting. Since the reflowed solder is prevented from being melted during the soldering by the jet solder, it is not necessary to lower the temperature of the molten solder in the jet solder bath 20. for that reason,
There is no need to use solder containing low melting point lead,
Lead-free solder can be achieved. Also, by preventing the reflowed solder from re-melting, the circuit board 6 caused by cracks or cracks in the reflowed solder can be prevented.
0 can be prevented from occurring.

According to the soldering method using the soldering apparatus 1 of this embodiment, room temperature air is used for cooling the circuit board 60. Therefore, it is possible to divert compressed air supply equipment normally installed in various manufacturing equipment,
Cooling equipment can be added at low cost. Further, since room temperature air is used, equipment for cooling the air is not required.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a soldering apparatus according to one embodiment of the present invention.

FIG. 2 is a schematic plan view showing the vicinity of a jet solder bath of the soldering apparatus according to one embodiment of the present invention.

FIG. 3 is a graph showing a temperature change of a circuit board to which a soldering method according to an embodiment of the present invention is applied and a temperature change of a conventional circuit board.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 soldering device 10 reflow furnace 20 jet solder tank 30 transfer device 40 cooling device 41 jetting unit 42 air pump (supply unit) 43 air tank (supply unit) 44 valve 45 detection unit 46 control unit 47 air pipe (supply unit) 60 circuit board

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 1/08 320 B23K 1/08 320Z 3/00 310 3/00 310C (72) Inventor Takaaki Suda Nagano 3-3-5 Yamato, Suwa-shi Seiko Epson Corporation F term (reference) 4E080 AA01 AB06 AB10 5E319 CC24 CC36 CD60 GG15

Claims (6)

[Claims] 1. A reflow furnace for reflowing solder provided on a circuit board, a jet solder bath for applying molten solder to one surface side of the circuit board which has been reflowed in the reflow furnace, and the jet solder A cooling unit installed above the tank and capable of cooling the surface of the circuit board opposite to the molten solder tank; and a conveying unit on which the circuit board is mounted and conveying the circuit board to the jet solder tank. A soldering device comprising: 2. The cooling means is provided at an ejection side capable of ejecting air, a supply part capable of supplying air to the ejection part, and an inlet side of the jet solder bath and mounted on the transport means. The solder according to claim 1, further comprising: a detection unit that detects the circuit board; and a control unit that supplies air from the supply unit to the ejection unit when the detection unit detects the circuit board. Mounting device. 3. A solder for a circuit board, wherein a solder provided on a circuit board is reflowed in a reflow furnace, and one side of the reflowed circuit board is subjected to jet soldering in a jet solder bath. A method of soldering, comprising cooling a surface of the circuit board opposite to the jet solder bath when performing the jet soldering. 4. A solder for a circuit board, wherein the solder provided on the circuit board is reflowed in a reflow furnace, and the one side of the reflowed circuit board is subjected to jet soldering in a jet solder bath. A soldering method, wherein air is blown onto a surface of the circuit board opposite to the jet solder bath when the jet soldering is performed. 5. The soldering method according to claim 4, wherein the circuit board is blown with air when the circuit board is transported to the jet soldering bath. 6. The air blown to the circuit board,
6. The soldering method according to claim 4, wherein the temperature is room temperature.