JPH05329630A - Device for soldering in low-oxygen concentration atmosphere - Google Patents

Abstract

PURPOSE:To suppress the splashing of the solder particles generated by falling of the jet waves of solder melts and the bouncing back thereof in a low-oxygen concn. atmosphere. CONSTITUTION:A solder tank 11 is provided in a chamber 22 and the solder melts 15, 16 are stored in this solder tank 11. The low-oxygen concn. atmosphere consisting of an inert gas is maintained in the chamber 22. Shielding plates 23 for suppressing the splashing of the solder particles 15d, 16d generated by the falling of the first jet waves 15a, 15b jetting from a first jet tank 17 in the solder tank 11, the second jet waves 16a jetting from a second jet tank 18 and the overflow waves 16b overflowing from a storage tank 21 onto liquid surfaces 15c, 16c and the bounding back thereof are provided near the points where the respective jet waves 15a, 15b, 16a and the overflowing waves 16b fall. As a result, the adhesion of the solder particles 15d, 16d to a printed circuit board 1 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low oxygen concentration atmosphere soldering apparatus for providing a solder bath in a chamber, filling the chamber with an inert gas, and performing soldering in a low oxygen concentration atmosphere. is there.

[0002]

2. Description of the Related Art FIG. 2 is a side sectional view showing an example of a conventional jet type solder bath. In this figure, reference numeral 1 is a printed circuit board, which is held by a carrying means such as a carrying conveyor 4 and carried in the direction of arrow A. Reference numeral 2 is an electronic component such as a resistor, capacitor, or IC temporarily attached to the printed board 1, and 3 is a lead wire or lead terminal of the electronic component 2. A jet type solder bath 11 is housed in a low oxygen concentration atmosphere in a chamber 22 described later. The solder bath 11 has a partition wall 12
Are formed in the primary tank 13 and the secondary tank 14, and are sequentially arranged in the conveying direction of the printed circuit board 1 (direction of arrow A), and the solder melts 15 and 16 are stored in each. Reference numerals 17 and 18 denote a first jet tank and a second jet tank which are arranged in the primary tank 13 and the secondary tank 14, respectively, and pressurize the solder melts 15 and 16 by driving a motor (not shown) to make jets. Jets are forcibly ejected from the mouths 19 and 20. Further, first jet waves 15a and 15b are formed from the jet port 19 in a substantially symmetrical shape with respect to the front-rear direction of the transport direction (arrow A direction) of the printed circuit board 1. In addition, the jet port 20 has a storage tank 2
1 is formed, and the solder melt 16 is jetted from the jet port 20.
While the solder melt 16 is stored in the storage tank 21, the solder melt 16 is jetted in a direction opposite to the conveying direction (arrow A direction) of the printed circuit board 1 to form a second jet wave 16a. The overflow wave 16b is formed by overflowing in the same direction as the traveling direction of the printed circuit board 1 (direction of arrow A). Also,
15c and 16c are the solder melts 1 in the tanks 13 and 14, respectively.
5, 16 and 15d, 16d are the jet waves 15
a, 15b, 16a and overflow wave 16b are solder melt 1
When dropped onto the liquid surfaces 15c and 16c of Nos. 5 and 16, the solder particles are scattered due to the rebound of the solder melts 15 and 16, and the solder particles 15d and 16d are generated in the low oxygen concentration atmosphere. Further, the chamber 22 (only a part of which is shown in FIG. 2) is arranged so as to penetrate the transport conveyor 4 of the printed circuit board 1, and accommodates a preheating device (not shown) and the solder bath 11, and Inert gas supply source (not shown) in the chamber 22
Is supplied with the inert gas from the nozzles, and the jet waves 15a, 15b, 16a, the overflow wave 16b, and the liquid surfaces 15c, 16c in the solder bath 11 are kept in a low oxygen concentration atmosphere due to the inert gas filling. There is.

Next, the operation will be described. The printed circuit board 1 is pre-heated by a pre-heating device (not shown) after mounting the electronic component 2, and then the first jet tank 17 uses the first jet waves 15a and 15b to melt the solder melt on the lead wire 3. 15
Blend in well. Then, the second jet tank 18
With the jet wave 16a and the overflow wave 16b, finish soldering is performed which is both a jet type and a flow dip type.

[0004]

By the way, when the atmosphere of the jet type solder bath 11 is an atmosphere having a normal oxygen concentration, the liquid levels 15c and 16c of the solder melts 15 and 16 are obtained.
Is in contact with the atmosphere, an oxide film is generated by oxygen in the atmosphere on the liquid surfaces 15c and 16c, and when the surface tension generated by this oxide film is the viscosity of the solder melts 15 and 16, a relatively large value is obtained. become. Therefore, the liquid surface 15c, 1
Each jet wave 15a, 15b, 16a and overflow wave 16 on 6c
Even when b was dropped on the liquid surfaces 15c and 16c of the solder melts 15 and 16, the solder particles 15d and 16d which were scattered due to the rebound of the solder melts 15 and 16 were hard to be generated.

However, when the liquid surfaces 15c and 16c of the solder melts 15 and 16 in the jet type solder bath 11 are in an atmosphere of low oxygen concentration, the oxide film decreases and the liquid surface 15c,
Since the viscosity of 16c becomes small, the solder melt 15, 16
There is a problem that the solder particles 15d and 16d are easily scattered due to the rebound.

FIG. 3 shows the liquid surface 15 of the solder melts 15 and 16.
concentration of oxygen in the atmosphere or the inert gas atmosphere on c, 16c and the liquid surface 15c, 1 of the solder melts 15, 16
It is a characteristic view which shows the result of having measured the relationship with the viscosity in 6c part with the viscometer. As can be seen from FIG. 3, when the oxygen concentration is reduced while supplying the inert gas into the chamber 22 having the same oxygen concentration as in the atmosphere, the viscosities of the liquid surfaces 15c and 16c of the solder melts 15 and 16 are increased. Although the oxygen concentration decreases at a substantially constant rate, when the oxygen concentration reaches a predetermined value, even if the oxygen concentration is reduced to a predetermined value or less to reduce the oxygen concentration, the liquid level 1 of the solder melts 15 and 16 is reduced.
The viscosities of 5c and 16c do not become small and become almost constant.

Therefore, when the oxygen concentration is the same as in the atmosphere, each jet wave 1 flowing out from each jet port 19 and 20
Since 5a, 15b, 16a come into contact with the atmosphere to form an oxide film, it is difficult for the solder particles 15d, 16d to scatter, but when an inert gas is supplied to reduce the oxygen concentration, the solder melt that flows out Liquids 15 and 16 and liquid surfaces 15c and 16
Since an oxide film is less likely to be generated on c, the viscosity is reduced, and each jet wave 15a, 15b, 16a and overflow wave 16b is generated on the liquid surface 1.
The solder particles 15d and 16d generated by dropping onto the 5c and 16c are easily scattered, and are scattered to the side of the upper surface side of the printed circuit board 1 which is not the soldering surface and adhere to the electronic component 2. Damage or IC
When it adheres to the lead terminals 3 on the upper surface side of the printed circuit board 1, there is a problem in that a short circuit due to a bridge may occur and the quality of the printed circuit board 1 may deteriorate.

Further, if the solder particles 15d and 16d are scattered around the jet-type solder bath 11, there is a problem in that they adhere to peripheral devices and cause troubles.

The present invention has been made in order to solve the above-mentioned problems, and is to provide a shield plate for suppressing the scattering of solder particles generated by the jet wave falling on the liquid surface of the solder melt and rebounding. Accordingly, it is an object of the present invention to provide a low oxygen concentration atmosphere soldering device in which solder particles are prevented from adhering to a printed circuit board.

[0010]

The low oxygen concentration atmosphere soldering apparatus according to the present invention is provided with a shield plate for suppressing the scattering of solder particles in the vicinity of the jet wave jetted from the jet tank.

[0011]

In the present invention, when the jet wave falls on the liquid surface of the solder melt, the scattering of the solder particles generated by the rebound is suppressed by the shield plate, so that the solder particles scatter and the printed circuit board and peripheral equipment It is possible to prevent the adherence to the kind.

[0012]

FIG. 1 is a side sectional view showing an embodiment of the present invention.
The same reference numerals as those in FIG. 2 indicate the same parts, and 23 is a shield plate, which is a solder particle 15d generated by splashing when the jet waves 15a, 15b, 16a and the overflow wave 16b drop on the liquid surfaces 15c, 16c. , 16d to prevent them from adhering to the printed circuit board 1.
a, 15b, 16a and the solder waves 15d, 16d in the vicinity where the overflow wave 16b falls are provided at a position where they can be repelled.

As described above, since the shield plate 23 is provided, the solder particles 15d and 16d are scattered and the printed circuit board 1
It is possible to prevent it from adhering to the upper surface of the device or to the equipment around the solder bath 11.

In the embodiment of FIG. 1, the two-tank type solder tank 11 is shown as an example, but the shield plate 23 is a one-tank type including only the primary tank 13 having the first jet tank 17. Alternatively, the solder tank may be provided in a single-tank-type solder tank such as the above-mentioned solder tank or a solder tank including only the secondary tank 14 including the second jet tank 18.

[0015]

As described above, according to the present invention, since the shield plate for suppressing the scattering of the solder particles is provided in the vicinity of the jet wave jetted from the jet tank, the electronic components and the leads on the upper surface side of the printed board are provided. It is possible to prevent solder particles from adhering to the terminals and damaging them, or to prevent the formation of bridges.
As well as improving the quality and productivity of printed circuit boards,
It has the advantage that troubles of the equipment around the solder bath can be prevented.

[Brief description of drawings]

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

FIG. 2 is a side sectional view showing an example of a conventional jet solder bath.

FIG. 3 is a characteristic diagram showing the relationship between the oxygen concentration in the atmosphere or an inert gas atmosphere and the viscosity of the solder melt at the liquid surface portion.

[Explanation of symbols]

 1 Printed Circuit Board 2 Electronic Component 3 Lead Wire 11 Solder Tank 13 Primary Tank 14 Secondary Tank 15 Solder Melt 15a First Jet Wave 15b First Jet Wave 15c Liquid Level 15d Solder Grain 16 Solder Melt 16a Second Jet wave 16b Overflow wave 16c Liquid level 16d Solder particles 17 First jet tank 18 Second jet tank 21 Reservoir tank 22 Chamber 23 Shield plate

Claims (1)

[Claims] 1. A solder bath having a jet bath for accommodating the solder melt and for soldering by pressurizing the solder melt to jet a jet wave, and a chamber covering the solder bath, In a low oxygen concentration atmosphere soldering apparatus in which the chamber is filled with an inert gas and the solder bath is kept in a low oxygen concentration atmosphere, a shield plate for suppressing scattering of solder particles is provided in the vicinity of the jet wave falling. A low oxygen concentration atmosphere soldering device characterized in that