JP3424102B2 - Soldering method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is related to <br/> the soldering where, in particular, when soldering the IC or the like to the substrate and the solder part in an inert gas atmosphere such as nitrogen gas about the way that is suitable for.

[0002]

2. Description of the Related Art To mount an electronic component such as an IC on a substrate by surface mounting, the electronic component is mounted on an electrode portion of a circuit pattern such as a copper foil formed on the substrate and then contacted with molten solder. A reflow method is known in which cream solder, which is a mixture of solder and flux, is used and an electronic component is placed thereon and heat-treated.

Conventionally, such heat treatment of solder has been carried out in the atmosphere, but in the atmosphere, the circuit pattern made of copper foil or the like and the solder are easily oxidized by heating,
Since the wetting property of the solder deteriorates and the electronic parts cannot be bonded well to the board, and the flux used for cream solder in the reflow method remains on the board after the heat treatment, it is necessary to clean the CFCs to remove this flux. There was a problem such as becoming.

As a remedy for this, a method of performing heat treatment in a nitrogen gas atmosphere containing almost no oxygen so that the circuit pattern and the solder are not oxidized has been widely used.

[0005]

However, most of the above-described soldering devices using a nitrogen atmosphere are relatively large devices that continuously process substrates, and the entire soldering part is hermetically sealed to remove nitrogen. It was supplied to create the atmosphere.
Therefore, the device for soldering a small amount is a large-sized device downsized in its original shape, and it is necessary to replace the atmosphere in the soldering furnace with nitrogen even when the substrate is not in the furnace. There was no choice but to use nitrogen.

Further, in a soldering robot or the like for soldering each substrate, it is necessary to place the robot in a nitrogen atmosphere. Therefore, a large amount of nitrogen is required. It was a difficult situation for soldering itself.

On the other hand, it is easily conceived to blow nitrogen to the soldering iron and create a nitrogen atmosphere near the soldering iron. However, there is no data that actually implements this and measures the oxygen concentration of the nitrogen atmosphere created thereby. Furthermore, there has been no study on how to arrange the nitrogen ejection nozzle with respect to the soldering iron to easily form a nitrogen atmosphere and to save the amount of nitrogen used.

Therefore, the present invention can form a desired inert gas atmosphere only in the soldering portion during soldering and can keep the soldering portion in an extremely low oxygen concentration atmosphere. and its object is to provide a soldering where capable of forming an inert gas atmosphere required significantly less inert gas supply amount Te.

[0009]

In order to achieve the above-mentioned object, the soldering method of the present invention is a nozzle in which the gas ejection port at the tip of the nozzle is arranged within 15 mm, preferably within 10 mm, of the soldered part. from the inert gas toward the solder part, for example, nitrogen gas per second 1 0-3
Eject at a flow velocity of 0 m, and the acid of the soldering part
The oxygen concentration was below 0.5% you are and performing soldering.

[0010] In addition, the present invention, the above-described configuration smell Te, before
To preheat the inert gas ejected from the serial nozzle,
The nozzle is configured to move in synchronization with the movement of the soldering iron, and the nozzle and the soldering iron are integrally formed.

[0011]

[Operation] According to the above configuration, it is possible to keep only the soldered portion in an inert gas atmosphere with an extremely low oxygen concentration,
Further, since the inert gas only needs to be ejected when soldering is performed, the amount of the inert gas used can be significantly reduced. Nitrogen is usually used as the inert gas, but noble gases such as argon, helium, and neon can also be used.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail based on an embodiment shown in the drawings. First, in FIG. 1, the soldering iron 1 and the nozzle 2 are separately formed, and the gas ejected from the nozzle 2 is arranged so as to be ejected toward the soldering portion 4 of the substrate 3.

In the nozzle 2, the distance between the ejection port 2a at the tip and the soldering portion 4 is within 15 mm, preferably 10 m.
It is arranged so that it is within m, and the ejection port 2a
The flow rate of the inert gas, such as nitrogen gas, ejected from the chamber is set to 5 m or more per second, preferably 10 to 30 m per second.

The distance between the jet port 2a and the soldering portion 4 and the gas flow rate are important factors for saving the amount of inert gas used and maintaining the atmosphere of the soldering portion 4 at a low oxygen concentration. Therefore, it can be appropriately set according to the configuration of the soldering device, the size of the soldering iron, the state of the soldering portion, and the like. For example, the ejection port 2a and the soldering portion 4
It is desirable that the distance between and is as close as possible. If this distance is 15 mm or more, it is necessary to increase the flow rate and flow rate of the inert gas in order to make the soldering portion 4 have a sufficient inert gas atmosphere. On the other hand, if the distance between them is too short, the nozzle may come into contact with the soldering iron or the board, which may hinder the soldering operation.

On the other hand, the flow velocity of the inert gas ejected from the nozzle 2 is different depending on the distance between the ejection port 2a and the soldering portion 4 and the area of the ejection port 2a, but the inert gas flowing through the soldering portion 4 is sufficiently inert gas. In order to create an atmosphere, it is preferable to make the flow rate as high as possible. However, the flow velocity is 30m / s
Even if the value exceeds, the inert gas atmosphere of the soldering portion 4 hardly changes, and the amount of the inert gas used only increases. The flow velocity of the inert gas can be reduced if the distance between the ejection port 2a and the soldering portion 4 is small, and the flow velocity can be reduced even when the flow amount of the inert gas is large.

That is, in order to make the atmosphere of the soldering part 4 have a desired composition and reduce the amount of the inert gas used, the ejection port 2a for ejecting the inert gas should be as close to the soldering part 4 as possible. It is effective to reduce the area of the ejection port 2a and increase the flow velocity with respect to the flow rate of the inert gas. For example, an atmosphere having a desired oxygen concentration can be formed by sending an inert gas flow having the above flow rate to the tip portion of the soldering iron 1 using the nozzle 2 having a diameter of 1 to 2 mm.

Here, the permissible oxygen concentration in the inert gas atmosphere required for soldering is not always constant depending on the properties of the solder and the flux used, but when general solder is used, the oxygen concentration in the atmosphere is 0. By setting the content to 0.5% or less, it is possible to suppress oxidation of the solder and perform good soldering.

Further, by heating the inert gas ejected from the nozzle 2 in advance, the oxygen concentration in the atmosphere formed in the soldering portion 4 can be lowered, and the inert gas is not added. By heating, it is possible to prevent the temperature of the solder from lowering.
It is desirable to eject the heat after preheating to 00 ° C or higher, preferably 100 to 300 ° C.

The soldering iron 1 and the nozzle 2 may be integrally supported by, for example, a bracket, or the soldering iron 1 and the nozzle 2 may be attached to different robot arms so as to be interlocked with each other. The inert gas ejected from the nozzle 2 may be constantly supplied to the tip portion of the soldering iron 1 or the soldering portion 4.

Further, as shown in FIG. 2, the periphery of the soldering iron 1 is surrounded by a pipe 5 for supplying an inert gas, and the soldering portion 4 of the substrate 3 is interposed between the pipe 5 and the soldering iron 1. Alternatively, an inert gas may be jetted.

In this case, the nozzle 2 does not interfere with the operation of the soldering iron 1 as compared with the embodiment shown in FIG. 1, which is convenient.
It is more effective to supply the inert gas in a slightly inclined state toward the tip of the soldering iron 1 than to supply the soldering part 4 at a right angle, in order to reduce the oxygen concentration in the soldering portion 4.

The nozzle for ejecting the inert gas may be arranged concentrically with respect to the soldering iron 1 as shown in FIG. 2, or a plurality of nozzles may be provided around the soldering iron 1. It may be arranged.

Nitrogen gas was used as the inert gas, and soldering was performed under the following conditions using the apparatus having the configuration shown in FIG. Soldering part 4 against the flow rate of nitrogen gas at this time
Fig. 3 shows the oxygen concentration of.

Distance between soldering part 4 and nozzle 2: 7 mm, 15 mm Nitrogen gas temperature: normal temperature, 100 ° C. Supply nitrogen gas purity: oxygen concentration 10 p
pm In addition, even when the apparatus having the configuration shown in FIG. 2 was used, substantially the same result as the above was obtained.

[0025]

As described above, according to the present invention, since the inert gas such as nitrogen gas is ejected to the soldering portion from the nozzle arranged in the vicinity of the soldering portion, good soldering can be achieved. It is possible to easily form an inert gas atmosphere for performing, and it is possible to significantly reduce the amount of the inert gas required to form the atmosphere.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing another embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a flow rate of nitrogen gas ejected from a nozzle and an oxygen concentration in a soldered portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Soldering iron 2 ... Nozzle 2a ... Jet outlet 3 ... Board 4 ... Soldering part

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Claims (3)

(57) [Claims] 1. An inert gas is jetted toward the soldered portion at a flow rate of 10 to 30 m / sec from a nozzle in which a gas jet port at the tip of the nozzle is arranged within 15 mm from the soldered portion , Oxygen concentration of the soldered part
A soldering method characterized by performing soldering at 0.5% or less . 2. The inert gas ejected from the nozzle is
The soldering method according to claim 1, wherein the soldering is performed in advance . 3. A nozzle for ejecting an inert gas is solder
The soldering method according to claim 1, wherein the soldering method is formed integrally with the iron .