JPH0741409B2 - Conveyor type non-oxidizing soldering device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveyor type non-oxidizing soldering apparatus for performing non-oxidizing soldering while automatically conveying a soldered article such as a printed wiring board on a conveyor.

[0002]

2. Description of the Related Art Conventionally, there is known a technique of wrapping a soldering atmosphere with nitrogen gas in order to prevent oxidation of a printed circuit board at a high temperature. However, since flux such as pine and lantern was used and flux was used, an acidic residue remained even after soldering in a nitrogen atmosphere, and a cleaning step with liquefied chlorofluorocarbon was required to remove it. Further, the conventional commercially available conveyor-type automatic soldering machine has a drawback that it consumes a large amount of nitrogen of 30 cubic rice per hour in order to prevent oxidation at a high temperature. Of these, the latter of the nitrogen consumption
Regarding the problem, for example, Japanese Patent Laid-Open No. 63-174778
Soldering is carried out in the report and Japanese Unexamined Patent Publication No. 2-303675.
The chamber has a closed structure, on which a conveyor or print
Soldered by providing an opening / closing door for passing the board
A technique for reducing the amount of nitrogen consumed during shaving is disclosed.

[0003]

However, the above-mentioned Japanese Patent Laid-Open No.
In the device described in JP-A-63-174778,
Inert gas supply port on the ceiling away from the rice field
Is installed, and an inert gas is inserted from the supply port into the room with the solder bath.
Since it is designed to supply solder, it is originally soldered
Inert gas that is sufficient only in the peripheral area of
It is necessary to meet all
It is hard to say that the active gas is supplied efficiently. one
On the other hand, in the device described in the above-mentioned Japanese Patent Laid-Open No. 2-303675.
Is provided with a supply port for supplying an inert gas above the solder bath.
Although it is being filled, it was filled in the room in that way
A special outlet is provided to actively discharge the inert gas.
Air is not removed from the room when soldering starts.
While it is necessary to supply a large amount of inert gas,
If necessary, collect the inert gas supplied to the room.
There is a drawback that you cannot do it even if you try to reuse it. It
Furthermore, in these technologies, the temperature of the inert gas is limited.
Is not considered at all, so soldering at high temperature
When an inert gas is supplied to an article, the temperature difference between the two causes
Causing thermal damage to the soldered item.
And the solder temperature of the part to be soldered is low.
There is a risk of causing soldering failure due to the bottom. Book
The invention was made in view of the above-mentioned circumstances.
An object of the present invention is to provide a conveyor-type non-oxidizing soldering device that consumes a small amount of an inert gas such as a raw gas and does not leave an acidic residue, and thus can omit the cleaning step using liquefied chlorofluorocarbon.

[0004]

Means for Solving the Problems A conveyor type non-oxidizing soldering apparatus of the present invention is provided with a solder tank for storing melted solder immediately below a predetermined position on a traveling track of a conveyor for carrying articles to be soldered, In a device provided with a solder circulation device that supplies the lower surface of the article to be soldered while circulating the molten solder, and a furnace core tube that blocks the conveyor passage before and after the predetermined position from the outside without hindering the traveling of the conveyor. , Specially configured as follows
To collect. That is, through the periphery of the solder bath, the peripheral portion of the predetermined position is preheated from its lower side to a predetermined temperature.
And the inert gas supply passage for supplying an inert gas, the predetermined position and the periphery upwardly disposed gas outlet, the travel and the object to be solder of the conveyor is provided before and after the predetermined position of the core tube A pair of semi-shielding means of a goodwill-like flexible structure that allows passage of attached articles and provides resistance to the inside and outside, and a space from the inside of the position where the pair of semi-shielding means is arranged to the outlet. Equipped with a partition device
It And, of these, the partition device,
The inert gas supplied from the lower side to the periphery is above it.
Of the pair of gas flows to the discharge port located in one direction.
From the inside of the position where the semi-shielding means is installed, taper toward the outlet.
Formed by a partition plate arranged in a tapered shape
On the other hand, on the article intake side of the conveyor,
Flack that applies alcohol-based flux to attached articles
A coating device is connected.

[0005]

In the soldered article, for example, a predetermined circuit element is arranged on a printed wiring board, and a lead wire to be soldered is slightly projected from the back surface (lower surface) of the board, before being placed on the conveyor. on the back surface front side of the substrate, the co
Flux applicator connected to the product intake side of the Nvea
Alcohol-based flux is applied in advance by. The article to be soldered is conveyed by a conveyor and passes over the solder bath. At this time, the back surface of the substrate is dipped in molten solder for soldering.

The inert gas flows through the periphery of the solder bath.
Is supplied to the peripheral part of a predetermined position above the
After wrapping the article to be soldered, exhaust gas above it.
It flows to the exit. In other words, supply from the inert gas supply passage
The inert gas is immersed in molten solder
Concentrate from the lower side to the upper side as if wrapping
Flow to. Therefore, the amount of inert gas supplied is relatively small.
Efficiently keeps the soldered article in a non-oxidized state
be able to. In addition, the inert gas supplied at this time is
Since it has been preheated to the specified temperature, it does not heat the article to be soldered.
Damage due to unevenness or bad soldering
There is no fear of causing it. Moreover, on the conveyor transport path in the furnace core tube
Before and after the prescribed position, semi-shielding means for "goodwill" is provided.
Taper from the inside toward the gas outlet
A partitioning device consisting of partition plates arranged in a
Therefore, the volume of the inert gas atmosphere is kept as small as possible.
The inert gas that has flowed upwards is separated
Guided by the plate, it does not spread horizontally
Smoothly flows into the exit. This allows the inert gas
The consumption of can be kept low. On the other hand, the outlet is
The air around the predetermined position is actively discharged in the initial stage. But
Therefore, it is not necessary to expel the initial air with an inert gas.
Therefore, the initial consumption of inert gas can be saved accordingly.
You can Moreover, after that, it was partitioned by a semi-shielding means.
To keep the internal inert gas pressure slightly higher than atmospheric pressure,
The outlet is controlled to the extent that the excess inert gas inside is drawn.
Be done.

When soldering with an alcohol-based flux, the flux component is not scattered and remains due to the heat during the soldering, so that a cleaning process after the soldering process is not necessary.

[0008]

Embodiment FIG. 1 shows a sectional view of an embodiment of the present invention. A board-like soldered article 1 such as a printed wiring board is conveyed from the right to the left in the figure, and a forward path of a conveyor 2 is stretched by 3 to 8 °, and an article intake section 3 is provided at a forward end of the forward path. ,
An article take-out section 4 is provided at the end of the outward path, and an elongated furnace core tube 5 that allows passage of the outward path of the conveyor is provided between them. Shutters 6 and 7 are provided at the entrance and exit of the furnace core tube 5 to allow only the conveyor 2 to travel, and are opened only when the article 1 to be conveyed passes, and closed except for the other cases. Further, the outlets 8 and 9 for initially discharging the air that has entered the furnace core tube 5 from the shutters 6 and 7 are the shutters 6 and 7, respectively.
Is provided in the vicinity of the inside.

A solder tank 10 is provided below the conveyor forward path at the center of the furnace core tube 5. This solder bath 10
Includes a pump 11 provided at the lower end of the pump 11 and an ejection pipe 12 that guides the pumping output upward, the molten solder reflows (reflow type), and the molten solder ejected upward from the ejection pipe 12 is an article to be soldered ( The liquid level is adjusted so as to wash the back surface of the conveyed article).

An inert gas supply passage 13 is provided through the periphery of the solder bath 10 and the pump 11 and has an upper end communicating with the furnace core tube 5 and a lower end communicating with an inert gas source such as N _2. An inert gas preheating heater 15 is provided in communication with the pipe 14. In front of and behind the position where the solder bath 10 is disposed on the outward path of the conveyor 2, a Teflon film or a metal is provided to allow the traveling of the conveyor 2 and the passage of the article to be soldered 1 while giving resistance to the passage inside and outside a predetermined range. The flexible structure "goodwill" -like semi-shielding means 16 and 17 made of a film are provided, and a parcel-shaped partition plate 19 is formed between the inside and the inert gas discharge port 18. 5 around the partition plate 19 and the heat insulating material 20
Is provided. Blower 2 for the inert gas outlet 18
1 is provided, and the semi-shielding means 16 and 1 are provided at the initial stage of operation.
7. The air in the internal space, which is partitioned from the outside by the partition plate 19 etc., is discharged, and thereafter, the excess gas is discharged little by little such that the pressure of the inert gas filling the internal space is slightly higher than the large pressure. The rotation is controlled so that An oxygen concentration meter 22 for monitoring the oxygen concentration in this internal space is provided, an auxiliary inert gas inlet 23 is provided inside the semi-shielding means 17, and outside the other semi-shielding means 16. A preheat heater 24 is provided for preheating the article to be soldered.

A flux applying device (not shown) for applying an alcoholic flux to the article to be soldered 1 is connected to the preceding stage of the article receiving section 3. An example of the composition of the alcohol-based flux which is previously applied to the article to be soldered is mainly composed of alcohol acetone, ether, benzene and its derivatives having a boiling point of 30 to 160 ° C. (about 90%) and a boiling point of 170 to 320 °. Highly viscous polyhydric alcohol derivative such as glycerin or ethylene glycol of C is added by several% to 10%, and further, a solution containing 2-3% of organic halogen active material such as dimethylamine hydrochloride, aniline hydrochloride, glutamine hydrochloride. Is preferred.

FIG. 2 shows another embodiment of the solder circulating apparatus of the present invention. Two solder supply drums 25 and 26 having different diameters are provided on the liquid surface of the solder bath 10, and the tangential planes on both drums have the same gradient as the conveyor 2. Spiral grooves are formed on the outer circumference of each of the drums 25 and 26 so that the molten solder is wound up by the rotation of the drum. An inert gas supply passage 13 is formed around the solder bath 10 as in the above-described embodiment.

Nitrogen and argon are used as the inert gas of the present invention, and hydrogen of several% or less may be mixed to impart a reducing property.

[0014]

EFFECTS OF THE INVENTION According to the present invention, the amount of inert gas consumed is markedly reduced as compared with the conventional one, while keeping the atmosphere of the soldering part acid-free. Further, by using the alcohol-based flux, the residue of the flux does not remain, and the residue cleaning step becomes unnecessary.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the solder circulating apparatus of the present invention.

[Explanation of symbols]

 1 ... ・ Items to be soldered 2 ... Conveyor 5 ... Reactor core tube 10 ... Solder tank 11 ... Pump 13 ... Inert gas supply passage 16 ...・ Semi-shielding means (entrance) 17 ・ ・ ・ ・ ・ ・ Semi-shielding means (exit) 18 ・ ・ ・ ・ Inert gas discharge port 19 ・ ・ ・ ・ ・ ・ Partition plate 20 ・ ・ ・ ・ ・ ・ Insulating material 22 ・ ・ ・ ・ ・ ・ Oxygen concentration meter

Claims (1)

[Claims] 1. A solder tank for accumulating molten solder is provided immediately below a predetermined position on a traveling path of a conveyor for conveying articles to be soldered, and the molten solder is circulated and supplied to the lower surface of the articles to be soldered. the solder circulation device provided an apparatus equipped with a furnace tube for blocking the outside world without interfering with the travel of the conveyor before and after the conveyor path of the predetermined position, the periphery of the predetermined position through the periphery of the solder bath Gas supply passage for supplying an inert gas preheated to a predetermined temperature from a lower side thereof to the section, a gas discharge port arranged above the peripheral portion of the predetermined position, and before and after the predetermined position in the core tube. A pair of semi-shielding means of a goodwill-like flexible structure which is provided in the above and allows the passage of the above-mentioned conveyor and the passage of the article to be soldered, and gives a resistance to the inside and outside of the passage, A partitioning device for partitioning the space from the inside of the position where the covering means is provided to the discharge port from the outside ,
The partitioning device is located on the periphery of the above-mentioned predetermined position from below.
The discharge port above which the supplied inert gas is located
So as to flow to
The taper is tapered from the side toward the outlet.
Is formed by a partition plate that
On the product intake side of the
A flux applicator for applying coal-based flux is in contact
Conveyor type non-oxidizing soldering device characterized by being continued .