JPH0587354B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to a semiconductor integrated circuit element with a lead frame, to each lead portion of a large number of electronic components connected by a frame portion of a lead frame, or to a printed circuit board. The present invention relates to a solder dip processing apparatus used in a step of forming a surface layer of solder on a copper layer portion.

Prior Art During the manufacturing stage of electronic components manufactured or connected using lead frames, it is common practice to form a surface layer of solder on the lead portions of the components, and such surface layer is usually a deep layer. (immersion) process.

The molten solder in the liquid tank is constantly heated by a heater, and the electronic components that are fed into the liquid tank by a carrier or the like for the solder bath descend with their lead frames facing down and come into contact with the molten solder. do. The molten solder in the liquid tank is also jetted, and in this case, surface oxidation of the molten solder can be reduced and the contact can be made good.

Problems to be Solved by the Invention When the lead frame portion of an electronic component has a U-shaped cross section, both wing portions thereof can be brought into contact with molten solder at the same time. However, in the case of an electronic component using a flat lead frame, it is necessary to deep-process one wing, then turn it upside down and deep-process the other wing. It is necessary to wait until the molten solder that adhered to the wing part during the first deep treatment is completely solidified. For this reason, there was a problem in that the number of man-hours and processing time increased, making it difficult to improve processing efficiency.

Furthermore, even though only the lead portions require solder dipping, molten solder also adheres to the frame portion, which is extremely uneconomical.

Furthermore, there is another problem in that impurities precipitated from the lead portion mix into the molten solder in the liquid bath and accumulate, which tends to cause changes in the composition of the molten solder over time.

Means for Solving the Problems According to the present invention, a block body that is easily wetted by the molten solder is placed in a liquid tank containing molten solder so that its head protrudes from the surface of the molten solder. will be placed. The block body has a vertical slit for guiding the molten solder to a position higher than the liquid level, and has a horizontal slit in the head for passing an electronic component through the horizontal slit. is configured to have a T-shaped cross section with the vertical slit.

Function With this structure, the molten solder in the liquid layer rises through the vertical slits of the block with good wettability, reaches the horizontal slits higher than the liquid level, and is held by its own surface tension. be done. When the lead portion of the lead frame portion or the printed circuit board passes horizontally through the horizontal slit, the molten solder comes into contact with the metal surface, making it possible to perform a horizontal solder bath. Moreover, since the molten solder necessary for this solder bath is sequentially supplied from the liquid tank through vertical slits, impurities deposited from the lead parts or the printed circuit board side can mix into the molten solder in the liquid bath and accumulate. There's nothing to do. In addition, since the solder bath progresses within the slit, it is possible not only to minimize surface oxidation of the molten solder, but also to efficiently form a thin solder layer with good adhesion through the squeezing action as it passes through the slit. can do.

Furthermore, by arranging two such blocks symmetrically in parallel as a pair, both wings of a flat lead frame can be deep-treated simultaneously with each block, and the width or horizontal direction of the block can be deep-treated. By simply adjusting the effective depth of the slit to the lead passage width of the lead frame portion, solder dipping can be applied only to the portions that require a solder layer, and waste of solder can be prevented.

Embodiments Next, the present invention will be explained along with embodiments shown in the drawings.

As shown in FIG. 1, a liquid tank 2 containing molten solder 1 is connected to a sheathed heater 3 and a block body 4.
Built-in. A block body 4 made of a metal such as iron or nickel that is easily wetted by the molten solder 1 made of a eutectic alloy of lead and zinc has a plurality of vertical slits 5 as shown in FIG. Head 4a protruding from the liquid level of solder 1
It has one horizontal slit 6 in it. 7
indicates the block hanging bracket. The horizontal slit 6 has a T-shaped cross section with the vertical slit 5 and communicates with a cavity 8 for determining its effective depth A. The gap width B of the vertical slit 5 is 0.12 mm to 0.2 mm, and
Gap width C of horizontal slit 6 is 0.18mm~
Each can be set to 0.25mm.

The molten solder that has entered the vertical slit 5 crosses the liquid level 1a and reaches the horizontal slit 6, where it is held by its own surface tension. Then, the lead portion 10a of the lead frame portion 10 of the electronic component 9 to be processed is
As the lead portion 10a passes through the horizontal slit 6 in a horizontal position, the molten solder comes into contact with the lead portion 10a.

Since there are a plurality of vertical slits 5, the solder bath due to the contact is repeatedly and continuously performed, and moreover, this solder bath advances within the horizontal slits 6. On the other hand, since a large number of lead portions 10a of the lead frame 10 are lined up at a predetermined distance apart, even if the upper end of the vertical slit 5 is closed by the lead portion 10a passing therethrough, it is instantaneous; At the next instant, new molten solder is sequentially supplied through the vertical slits 5. Furthermore, since the frame portion 10b of the lead frame portion 10 passes through the cavity 8 and there is no molten solder within the cavity 8, no molten solder adheres to the frame portion 10b.

The whole or a part of the vertical slit 5 may be slightly inclined, or may be branched in the middle. Also, the depth dimension D of the block body 4
may be aligned with the depth A of the horizontal slit 6, and the side wall of the cavity 8 serves as a guide when transferring the electronic component to be processed.

The upper ends of the vertical slits 5 do not need to be perpendicular to the longitudinal direction of the horizontal slots 6; if they are inclined as in the embodiment shown in FIG. Supply can be increased. There may be only one vertical slit.

In the embodiment shown in FIG. 4, a pair of block bodies 4 are assembled so as to face each other, and the main body portion of the electronic component to be processed passes through an intermediate portion 11 thereof.

The transfer means for feeding the frame portion 10 of the electronic component 9 to be processed into and out of the block body 4 can be achieved by providing an appropriate number of pairs of rollers on the entrance and exit sides of the block body 4. The two rollers in each pair sandwich the frame portion 10a of the lead frame portion 10 from above and below to transport the electronic component to be processed.

Note that the electronic component to be processed is not limited to a semiconductor product, and may be a printed circuit board or the like.

Effects of the Invention As described above, according to the present invention, it is possible to achieve a horizontal solder bath for the lead portions of the lead frame portion within the horizontal slit, thereby minimizing surface oxidation of molten solder and always achieving good soldering. A surface layer can be formed. Also, the block 2
By arranging a pair of lead frame parts symmetrically, both wing parts of the flat lead frame can be soldered at the same time, and the width of the block body or the effective width of the horizontal slit can be adjusted to the width of the lead frame part. By simply adjusting the lead portion passage width, a solder surface layer can be formed only on the lead portions, and waste of molten solder can be prevented. Further, it is possible to prevent the molten solder in the liquid bath from changing over time, and to form a thin solder layer with good adhesion.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a solder dip processing apparatus embodying the present invention, Fig. 2 is a partially cutaway perspective view showing the relationship between the block body of the apparatus and electronic parts to be processed, and Figs. 3 and 4 are FIG. 7 is a perspective view of main parts of other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Molten solder, 2... Liquid bath, 4... Block body, 5... Vertical slit, 6... Horizontal slit, 9... Electronic component to be processed, 10... Lead frame portion, 10a... Lead part, 10b...
frame part.

Claims (1)

[Claims] 1. A block body that is easily wetted by the molten solder is disposed in a liquid tank containing molten solder so that its head protrudes from the liquid level of the molten solder, and the block body has the following properties: It has a vertical slit for guiding the molten solder to a position higher than the liquid level, and a horizontal slit for passing the electronic component through the head, and the horizontal slit is connected to the vertical slit. An electronic component solder dip processing device characterized by having a T-shaped cross section.