JP2003152327A - Method and device for soldering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for soldering an electronic part to a board, which is capable of protecting a soldered part against oxidation so as to enable solder to wet the part well and to spread over it well, preventing failures such as no solder, a lack of solder wettability and the like, heating the soldered part quickly and efficiently in a short time, and reducing its running cost. SOLUTION: A soldered part which is pre-heated up to a temperature of 100 deg.C or above is subjected to soldering in a high-temperature water vapor atmosphere kept at a temperature of 200 deg.C or above produced by an electromagnetic induction heating method. High-temperature water vapor can be produced by the use of a first heating means 8 which boils water to generate water vapor and a second heating means 9 which heats the generated vapor up to a prescribed high-temperature of 200 deg.C or above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for soldering mounted electronic components to a board.

[0002]

2. Description of the Related Art Generally, a reflow furnace is used as a heating method for soldering mounted electronic parts to a pattern formed on a printed circuit board using solder such as conductive paste. It is being appreciated.

Generally, a reflow furnace has a heating chamber, a soaking chamber, a main heating chamber, and the like having about 4 to 7 heating chambers arranged in series, and each chamber has a heating portion and temperature is adjusted. The board on which electronic components are mounted is soldered by passing through each of these chambers.

Here, the structure of the heating section is generally a combination of an electric heater or a far infrared heater and a hot air fan. The heating gas used at that time is generally atmospheric air or nitrogen gas.

When the atmosphere is used with these heated gases, the soldering portion of the substrate is oxidized and an oxide film is formed, so that the wetting and spreading of the solder is deteriorated, and defects such as unsoldered solder and insufficient wetting occur. It has the drawback of becoming easier. Therefore, in order to avoid this, it is necessary to make the heating chamber an oxygen-free or low-oxygen atmosphere, and nitrogen gas which is an inert gas is used. However, nitrogen gas has a drawback that the running cost is high.

Further, it has been proposed to use a reducing gas such as hydrogen in order to completely remove the generation of the oxide film, but this method still has a drawback that the running cost is high and its control is difficult. Have

Further, recently, there has been a demand for an efficient soldering method in which the heating speed of the soldering portion is fast and the heating time is short, but the above-mentioned conventional method has not been sufficiently satisfactory.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to prevent the progress of oxidation of the soldered portion and spread the wetness of the solder.・ Soldering is good for soldering electronic components to the board, which does not cause defects such as unsoldered or insufficient wetting, has a high heating rate at the soldered part, has a short heating time, and can reduce running costs. To provide a mounting method and device.

[0009]

That is, a first aspect of the present invention for achieving the above object is a method of soldering an electronic component mounted on a substrate to a substrate, which is a soldering part. Is performed in a steam atmosphere having a melting point of the solder or higher.

As described above, the first aspect of the present invention is basically to use steam as the heating gas. By doing so, the soldering part is basically kept in a low oxygen concentration state. It can prevent the progress of solder oxidization, spreads and wets the solder well, has no defects such as unsoldered or insufficient wetting, and has a high specific heat characteristic of water vapor, so the heating speed of the soldering part is fast, It is considered that the heating time is shortened, the steam is substantially inexpensive as a gas, and the electronic component can be soldered to the substrate which can reduce the running cost.

The second invention of the present invention is the same as the first invention, wherein the soldering is performed in a steam heating chamber. According to the present invention, it is possible to carry out a large amount of processing under the same heating condition and at the same time, regardless of the type of electronic component mounted on the substrate.

A third invention of the present invention is the same as the first invention, wherein the soldering is performed by spraying steam from a nozzle onto the soldering portion. According to the present invention, even if the electronic components mounted on the board are considerably different in material (heat resistance, heat capacity, etc.), shape, etc. from one component to another, and even if various types of electronic components are mounted, soldering is performed. Since the amount of water vapor sprayed to the attachment part can be controlled to a required state, the present invention can be efficiently implemented, especially when the electronic component is an insertion mounting component or a multi-component component.

A fourth invention of the present invention is the same as the third invention, wherein the soldering is performed in accordance with an electronic component such that the diameter of the steam outlet of the nozzle and / or the tip of the steam outlet of the nozzle and the soldering portion. This is done by adjusting the interval. According to the present invention, it is easy to adjust the soldering time at each location to be the same even if there are various and many soldering locations, and especially if the electronic component is an insertion mounting component or a multi-component component, The present invention can be carried out more efficiently.

A fifth aspect of the present invention is that in the first to fourth aspects of the invention, the substrate is preheated to 100 ° C. or higher and then soldered in a steam atmosphere. According to the present invention, since the entire substrate on which electronic components are mounted is heated to a uniform temperature in advance, soldering can be performed without temperature difference even when mounting various electronic components, so that the wettability of the solder can be improved. It enables soldering without lowering and without causing dew condensation on the substrate and components.

A sixth aspect of the present invention is the same as the first to fifth aspects, wherein the soldering is performed in a high temperature steam atmosphere of 200 ° C. or higher. According to this invention, the melting point of many solders in this field is 190 ° C.
Since the temperature is about 230 ° C., normally, under a high temperature steam atmosphere of 200 ° C. or higher, it becomes possible to easily and efficiently solder electronic components to a substrate.

Further, a seventh invention of the present invention is the same as the sixth invention, wherein the high-temperature steam is heated by boiling the water to generate steam, and the generated steam is heated to a predetermined temperature of 200 ° C. or higher. This is a method of generating it by the second heating means for heating to high temperature steam. According to the present invention, stable high-temperature steam can be supplied and the high-temperature can be easily adjusted, so that effective and efficient soldering is possible.

The eighth invention of the present invention is the method of using the electromagnetic induction heating as the heating means for generating water vapor in the seventh invention. According to the present invention, it is easy to set the temperature of the high temperature steam in an arbitrary and stable state by controlling the high frequency current, which not only enables more effective and efficient soldering, but also the temperature. Since the responsiveness when changing is also good, it does not require several heating chambers like the conventional reflow furnace, and the equipment can be simplified.

A ninth aspect of the present invention is the method for soldering a substrate according to the second aspect, wherein the electronic component is a surface mount component. According to the present invention, it is possible to carry out a large amount of processing under the same heating condition and at the same time, regardless of the type of electronic component mounted on the substrate.

The tenth invention of the present invention is the method for soldering a board according to the third or fourth invention, wherein the electronic component is an insert mounting component. According to the present invention, even if the electronic components mounted on the board are considerably different in material (heat resistance, heat capacity, etc.), shape, etc., it is possible to control the amount of water vapor sprayed to the soldering part to a required state. Therefore, more effective and efficient soldering is possible for these components.

The eleventh invention of the present invention is the method for soldering a substrate according to the third or fourth invention, wherein the electronic component is a multi-type electronic component. According to the present invention, even if a wide variety of electronic components are mounted on the board, the amount of water vapor sprayed onto the soldering portion can be controlled to a necessary state, so that it is more effective in these components. Enables efficient soldering.

A twelfth aspect of the present invention is a means for preheating a substrate on which electronic components are mounted to 100 ° C. or higher,
First steam generating means for boiling water to generate steam, second steam generating means for heating the generated steam to high temperature steam of 200 ° C. or higher, and soldering in a high temperature steam atmosphere of 200 ° C. or higher. A soldering device, comprising at least a soldering means for performing. According to this invention, at least means for achieving the above-mentioned method of the present invention are provided.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method and apparatus for soldering an electronic component on a substrate such as a printed wiring board to a conductive pattern formed on the substrate.
Solder is previously supplied on the conductive pattern by an arbitrary method such as screen printing, and the invention is suitable for the method in which the lead terminals (feet) of the electronic component are brought into contact with the conductive pattern to melt and solder the solder. However, it is also applicable to a method in which the solder itself is simultaneously supplied to the joint portion together with high temperature steam or by separate means to perform soldering.

In the present invention, the electronic component may be any one such as a capacitor, a resistor and an IC chip, and may be mounted on a substrate in any form. In the present invention, surface mount components, insertion mount components, and multi-type mount components as electronic components mean the following.

[Surface-Mounted Component] A lead terminal refers to an electronic component that is placed on a conductive pattern on the surface of the substrate without penetrating the substrate.

[Insertion-Mounted Component] An electronic component in which lead terminals extend to the opposite surface of the substrate through through holes (through holes) in the substrate, and the terminals are fixed to the substrate on this surface. There are quite a few types of electronic parts that have different shapes and heat capacities, or are weak against heat, so it is necessary to give due consideration to the supply of heated gas for each soldering part. There are things.

[Various types of electronic components] Electronic components mounted on the board are in various or various states. Like electronic components, such electronic components have different shapes and heat capacities partially,
Since it often contains heat-sensitive types,
After all, it may be necessary to give due consideration to the supply of heated gas at the time of soldering for each soldering part.

In the present invention, the atmosphere of the soldering part when soldering is carried out is a steam atmosphere.
The water vapor atmosphere in the present invention means that the atmosphere is in a water vapor state as it is, and the entire atmosphere does not have to be completely filled with water vapor.

However, it is generally preferable that the atmosphere is substantially in a water vapor state.
It is preferable to adjust the oxygen concentration to about 100 PPM or less at a temperature of 200 ° C. or higher.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view basically showing a configuration of an entire apparatus for carrying out the second invention of the present invention, and FIG. 2 is basically carrying out the third invention of the present invention. It is an explanatory view showing the configuration of the entire device for doing.

In FIG. 1, the soldering according to the present invention is carried out by preheating chamber 1 and steam heating chamber 2 provided adjacent to it.
In the heating furnace 3 composed of 1 and 2, the electronic component, preferably the substrate 5 on which the surface mount component 4 is mounted via solder (not shown) is placed on the conveyor 6 and transferred.

The preheating chamber 1 is heated by an electric heater or a far infrared heater in order to heat the substrate 5 to a predetermined temperature. The preheating chamber 1 is useful for maintaining a uniform temperature on the entire substrate on which electronic components are mounted and performing soldering with good durability and wettability in the steam heating chamber 2, and the entire substrate is 100 ° C. or higher, Up to about 200 ℃
The temperature is preferably adjusted to about 120 to 150 ° C.

For preheating, it is also effective to divide the preheating chamber 1 into several zones and raise the temperature sequentially. The preheating chamber 1 may not be provided continuously with the steam heating chamber 2 but may be heated in another heating chamber, but after heating to the predetermined temperature, the steam heating chamber 2 is heated as quickly as possible. Since it is preferable to carry out soldering, the preheating chamber 1 and the steam heating chamber 2 are preferably provided in succession.

Further, according to the present invention, it is possible to directly perform soldering in a steam atmosphere without preheating depending on the electronic component, but when the electronic component is an insertion mounting component or a multi-insertion component, Preheating is usually desirable because the conditions for soldering with good durability and wettability may be impaired due to the temperature difference between the parts.

It is also possible to carry out the preheating by heating with steam, but it cannot be said to be preferable at 100 ° C. or lower because dew condensation may occur.

The substrate 5 preheated to a predetermined temperature is then transferred to the steam heating chamber 2 by the conveyor 6 and soldered in a steam atmosphere, particularly in a high temperature steam atmosphere.

In the steam heating chamber 2, the steam temperature of the atmosphere to which the soldering part is exposed is 200 ° C. or higher because the melting point of the solder used in the present invention is about 190 ° C. to 230 ° C. preferable. Figure 1
In a steam heating chamber 2 such as
In order to uniformly perform any substrate under high temperature steam at a temperature of not less than 0 ° C., preferably about 210 to 250 ° C., it is necessary to keep the entire heating chamber 2 at a uniform temperature.

For this purpose, it is desirable that the temperature of the steam introduced into the steam heating chamber 2 be fairly high temperature steam, which is 300 to 400, although it depends on the size and structure of the steam heating chamber 2, electronic parts, and the like. It is to be introduced at about ℃. That is, it is desirable to introduce high temperature steam of about 300 to 400 ° C. into the steam heating chamber 2 and adjust the atmosphere temperature of the soldering portion to about 210 to 250 ° C.

For this purpose, it is necessary that such high-temperature steam can be stably supplied at an arbitrary temperature, and FIG. 1 shows a high-temperature steam generator for that purpose. .

The high-temperature steam generator 7 shown in FIG. 1 is basically a first electromagnetic induction heating device 8 which is a first steam generating means for boiling water 15 to generate steam. Generate water vapor at 200 ° C or higher, especially 300 to 4
It is composed of a second electromagnetic induction heating device 9 which is a second steam generating means for heating up to high temperature steam 25 of about 00 ° C.

In these devices, the method of generating water vapor is as follows.
A high-frequency current is supplied from a high-frequency current generator 11 to a coil 10 wound around the outer periphery of 8 to heat the metal heating element 12 disposed on the inner periphery of the non-conductive tubular body 18 so that water at room temperature is cooled. First bring to a boil. Then, the boiling water vapor can be further converted into high temperature water vapor 25 by the second electromagnetic induction heating device 9 by a similar heating method.

Here, the temperature of the steam can be set to an arbitrary temperature by controlling the high-frequency current, and when the temperature is changed, the steam can be directly heated by the metal heating element 12 so that the temperature of the steam responds. You can control it.

In FIG. 1, the first electromagnetic induction heating device 8
Between the second electromagnetic induction heating device 9 and the second electromagnetic induction heating device 9
3 is provided so that the amount of steam introduced (blown out) into the steam heating chamber 2 can be controlled. Excess steam can be returned to reheat through line 14.

The high-temperature steam generated by reheating in this manner has a high temperature of 300 to 400 ° C., which is different from ordinary visible white steam generated by the first electromagnetic induction heating device 8 and is different from the normal white steam. Is vapor in the invisible state of low oxygen and without moisture, which is very suitable for achieving the object of the present invention.

In FIG. 1, reference numeral 16 is a water level adjusting tank, 17 is a temperature sensor, and 18 is a case where steam generated by a normal boiler is used in place of the first electromagnetic induction heating device 8 or when necessary. It is a gas introduction port for other gases to be introduced as a result.

In FIG. 2, the soldering according to the present invention is performed on a substrate 5 on which electronic components preheated in a preheating chamber 1, preferably insertion or multi-mount components 4 are mounted via solder (not shown). It is carried out by spraying high-temperature steam 25 with a steam spraying device 21 having a nozzle 20 at a predetermined portion. In FIG. 1, a mode in which soldering in a steam atmosphere is performed in a steam heating chamber has been described, but in FIG. 2, a steam spraying device 21 having a nozzle 20 is used to remove high-temperature steam on a table 24 such as a conveyor. Although it is a mode to carry out by spraying,
Descriptions of common parts are omitted.

In FIG. 2, since it is possible to make the amount and temperature of water vapor blown out from nozzle to nozzle, even if the shape and properties of electronic components are different, the water vapor is sprayed according to them (the direction of water vapor spraying is , Upward, downward, etc.). In this case, the temperature of the high temperature steam sprayed from the nozzle 20 of the steam spraying device 21 to the soldering portion is 200 ° C. or higher, preferably about 210 to 250 ° C., as in the case of the embodiment of FIG. It is adjusted in the electromagnetic induction heating device 9 and the steam spraying device 21.

Each nozzle 2 is provided in the steam spraying device 21.
In order to make the amount and temperature of water vapor blown from 0 uniform,
A current plate 23 having a large number of through holes 22 is attached. Further, each nozzle 20 can be attached to the current plate 23 so as to be movable and removable.

Further, in this embodiment, the mounted electronic parts are almost different in shape and the like in most cases. Therefore, the wetting time of the solder is made constant at each place according to the shape and the like, and the defect is caused. It is preferable to reduce the occurrence rate. This can be performed by adjusting the diameter of the steam outlet of the nozzle 20 and / or the distance between the tip of the steam outlet of the nozzle 20 and the soldering portion according to the soldering point.
In addition, the steam outlet diameter (inner diameter) of the nozzle 20 is
It is preferably 1 to 5 mm, and the distance between the water vapor blowing tip of the nozzle 20 and the soldering portion is preferably 2 to 10 mm.

FIG. 3 shows an example of the water vapor spraying device 21 which enables such adjustment. In FIG. 3, the water vapor spraying device 21 includes at least a nozzle 20a having a small opening diameter (inner diameter) and a nozzle 20b having a large opening diameter (inner diameter). The nozzle 20a having a small inner diameter is used for the electronic component 4a which is a surface mount component mounted on the substrate 5, and the nozzle 20b having a large inner diameter is used for the electronic component 4b which is an insert mount component mounted on the substrate 5. By adjusting the spraying amount of the water vapor 25 according to the soldering portion, it is possible to perform the treatments simultaneously at a uniform time.

[0050]

EXAMPLE A printed wiring board made of glass fiber reinforced epoxy resin was used as a board, and an electronic component mounted on this board was mounted and mounted with its lead wires (two, lead diameter: 0.
8 mm) terminals were led out to the opposite surface of the board through a through hole and mounted on the board. The solder is SnAgCu.
A paste paste solder (melting point: 221 ° C.) was applied and intervened on the surface of the substrate to which the lead terminals were previously attached by a dispenser.

Then, this substrate was placed in a heating furnace using a far infrared heater as a heat source and heated to 150 ° C. for about 120 minutes. Immediately, the substrate taken out from the heating furnace was locally sprayed with high-temperature steam locally from the nozzle of the steam spraying device (opening inner diameter: 3 mm) to the soldering part to perform the soldering process.

The high temperature steam is generated by an electromagnetic induction heating device as shown in FIG. 2, and in the soldering part,
The temperature was adjusted to about 230 ° C. and the soldering time was about 15 seconds. During this period, no dew condensation on the electronic parts was observed.

When the soldering state of the board thus obtained was examined, it was found that the solder was attached without any cracks in any terminal portion, and the solder was wet and spread extremely. It was good. Further, when such soldering was repeated 20 times, the result was exactly the same.

[0054]

As described above, according to the present invention, basically, the atmosphere for soldering is set to the steam atmosphere to prevent the oxidation of the soldered portion from progressing, and to spread and wet the solder. Good, there are no defects such as unsoldered or insufficient wetting, the heating speed of the soldered part is fast,
The heating time is shortened, and it is possible to efficiently solder the electronic component to the substrate, which can reduce the running cost, and its practical value is extremely large.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration example of an entire device for carrying out the present invention.

FIG. 2 is an explanatory diagram showing another configuration example of the entire device for implementing the present invention.

FIG. 3 is an explanatory view showing an example of a steam spraying device for carrying out the present invention.

[Explanation of symbols]

1: Preheating room 2: Steam heating chamber 3: heating furnace 4, 4a, 4b: electronic components 5: substrate 7: High temperature steam generator 8: First electromagnetic induction heating device 9: Second electromagnetic induction heating device 10: coil 11: High frequency current generator 12: Metal heating element 13: Steam amount regulator 18: Non-conductive cylinder 20, 20a, 20b: nozzle 21: Steam spraying device 23: Current plate 25: Water vapor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshitaka Uchibori             19-21 Misawa Town, Ibaraki City, Osaka Prefecture Seta Co., Ltd.             Within Giken F-term (reference) 5E319 AA03 AA07 AB05 AC01 BB05                       CC58 CD29 GG15

Claims (12)

[Claims] 1. A soldering method for soldering an electronic component mounted on a substrate to a substrate, wherein the soldering portion is soldered in a steam atmosphere having a melting point of the solder or higher. 2. The soldering is carried out in a steam heating chamber.
Soldering method described. 3. The soldering method according to claim 1, wherein the soldering is performed by spraying steam from a nozzle onto the soldering portion. 4. The soldering method according to claim 3, wherein the soldering is performed by adjusting the steam outlet diameter of the nozzle and / or the distance between the steam outlet tip of the nozzle and the soldering portion according to the electronic component. 5. The substrate is preheated to 100 ° C. or higher and then soldered in a steam atmosphere.
Soldering method according to any one of. 6. The soldering method according to claim 1, wherein the soldering is performed in a high temperature steam atmosphere of 200 ° C. or higher. 7. High-temperature steam, first heating means for boiling water to generate steam, and steam generated at 200 ° C.
The soldering method according to claim 6, which is generated by the second heating means for heating the steam to the predetermined high temperature steam. 8. The soldering method according to claim 7, wherein the heating means is electromagnetic induction heating. 9. The soldering method according to claim 2, wherein the mounted electronic component is a surface mount component. 10. The soldering method according to claim 3, wherein the mounted electronic component is an insert mounting component. 11. The soldering method according to claim 3, wherein the mounted electronic components are various mounting components. 12. A means for preheating a substrate on which electronic components are mounted to 100 ° C. or higher, a first steam generating means for boiling water to generate steam, and the generated steam at 200 ° C.
A soldering device comprising at least a second steam generating means for heating to the above high temperature steam and a soldering means for performing soldering in a high temperature steam atmosphere of 200 ° C. or higher.