JPS6051938B2 - Immersion solder bath - Google Patents

Description

[Detailed description of the invention] The present invention relates to an immersion type solder bath.

Conventional immersion solder baths only store molten solder inside the solder bath body, but in this conventional solder bath, the electrodes at both ends of the chip components bonded to the bottom surface of the printed wiring board are When soldering to a pattern on a printed wiring board, the printed wiring board is lowered and its lower surface is dipped into the melted solder surface in the solder bath.
If the tip is moved further forward and lifted up to separate from the molten solder surface, a gas pool is likely to form in the soldered portion of the electrode portion at the rear end of the chip component, which may result in poor soldering.

The present invention was made in view of the above points, and an object of the present invention is to provide an immersion type soldering bath that can remove gas pools from the soldered parts at both ends of a chip component bonded to the bottom surface of a printed wiring board. The invention provides a rising port for the upward flow of molten solder that forms a protrusion on the surface of the molten solder inside the solder bath body, and a pump blade that circulates the molten solder in the upper part to the lower part of the rising port. The solder tank is arranged inside the solder tank body.

Next, one embodiment of the present invention will be described based on the drawings. A conveyance means for conveying the printed wiring board 2 while moving it up and down is provided above the solder bath main body 1 installed at a fixed position.

Lead wires of electronic components 3 are inserted into the printed wiring board 2 from above, and a chip component 5 is bonded to the lower surface of the printed wiring board 2 with an adhesive 4. The conveyance means for the printed wiring board 2 includes a carrier (not shown) holding the printed wiring board 2 which is movably placed on vertically moving rails (not shown) on both sides of the solder tank body 1, and also connected to a feeding chain (not shown) in a vertically movable manner. It comes together.

Further, a partition plate 7 is provided horizontally inside the solder bath main body 1, and a plurality of upward openings 11 for upward flow of molten solder 10 forming a raised portion 9 on the molten solder surface 8 are provided on this partition plate.

Also, a vertical partition plate 1 is provided on one side of the interior of the solder tank body 1.
3 forms a pump chamber 14, and a pump blade 15 is disposed in this pump chamber 14, and the pump blade 15 allows the molten solder 16 in the upper part to the lower part of the rising port 11 to
be circulated. The rotating shaft 17 of the pump blade 15 is rotationally driven by a motor 19 provided outside the solder bath body 1 via a bevel gear 18 . Then,
First, melt the solder surface 8 using a floating matter removing spatula (not shown).
After removing the oxides on the carrier and transporting the carrier by the feed chain, the printed wiring board 2 is transported horizontally along the transport path 21 at a constant height to one end of the solder tank body 1, and then the vertical movement rail was lowered from the forward side, and the printed wiring board 2 was carried into the solder tank main body 1 in a downwardly tilted forward state.Then, the vertically movable rail was gradually brought into a horizontally downwardly descending state, and the above-mentioned chip component 5 was bonded. The lower surface of the printed wiring board 2 is advanced while being horizontally immersed in the molten solder surface 8.

At this time, the electrode parts 22 and 23 at the front and rear ends of the chip component 5 and the corresponding patterns 24 and 25 of the printed wiring board 2 are soldered, and the lower surface of the printed wiring board 2 is the molten solder surface. 8 is detected by a limit switch (not shown), the pump blade 15 is driven, and an upward flow 10 of molten solder is generated from the rising port 11, and this upward flow 10 causes the molten solder surface 8 to A raised portion 9 is formed, and the rising flow 10 of the molten solder collides with the soldered portions 27 and 28 of the electrode portions 22 and 23 at both ends of the chip component 5 at the raised portion 9, and the impact causes the above-mentioned Soldering parts 27, 28
This soldering part 27, 28
to expel them from

This action is performed continuously while the printed wiring board 2 moves forward in a horizontally immersed state, and after a predetermined time, the pump blade 15 is stopped by a timer. Next, the vertically movable rail is raised from the forward side, and the printed wiring board 2 is carried out from the solder tank body 1 in a forward upward tilting state, and then in a horizontally rising state, and the printed wiring board 2 is sent to the next process. . As described above, according to the present invention, since a means for generating an upward flow of molten solder in an immersion type solder bath, that is, a rising port and a pump blade is provided, the upward flow is directed to the soldering portions at both ends of the chip component. This makes it possible to expel gas pools at the soldering part by colliding with the soldering part, and in particular, it is possible to reliably remove gas pools at the soldering part at the rear end of the chip component, which could not be removed by conventional soldering.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the immersion type solder bath of the present invention, FIG. 2 is a cross-sectional view taken along line 1-1 in FIG. 1, and FIG. 3 is a cross-sectional view of a bonded portion of a chip component. 1...Solder tank body, 8...Dissolved solder surface, 9...Elevated portion, 10...Upward flow of melted solder, 11...Rise Mouth, 15...Pump vane, 16...Melted solder.

Claims (1)

[Claims] 1 Inside the solder tank body, a rising opening for the upward flow of molten solder that forms a raised part on the molten solder surface is provided, and
An immersion type solder tank characterized in that a pump blade for circulating the melted solder in the upper part to the lower part of the rising port is disposed inside the solder tank main body.