JPH0671650B2 - Method and apparatus for replenishment of solder melt and removal of oxide film by rotary solder processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a package to be soldered, such as a semiconductor IC such as a hybrid IC or LSI, mainly on the outer leads of solder or tin (hereinafter simply referred to as solder). The present invention relates to a method for supplying a molten solder solution to a processing bath and removing an oxide film when performing a solder coating process for coating a film in a rotary solder processing bath, and an apparatus therefor.

[Conventional technology]

An outer package to be soldered, for example, an outer lead of a semiconductor package, is preliminarily coated with a solder film in order to efficiently and accurately perform a process for mounting on a printed circuit board. In addition, after mounting the semiconductor package on a printed circuit board, the outer leads protruding on the back surface may be soldered.

What has been generally performed conventionally as this solder exterior means is,
A solder plating method that forms a solder film on the outer leads of a semiconductor package by electroplating, and a solder melt that forms the solder film by immersing the outer leads of the semiconductor package in the solder melt and adhering and solidifying the solder melt It is a dipping method.

[Problems to be Solved by the Invention] Of the above-mentioned solder exterior means, in the solder plating method, the organic agent in the plating solution leaves an adverse effect on the wettability and performance of the solder, and also waste liquid and exhaust gas accompanying the plating process. Since a suburban treatment facility is required, it is difficult to incorporate it into a semiconductor package assembly process that requires high cleanliness. Further, solder plating treatment is performed in a state where each lead is connected by a tie bar, and then the tie bar is cut, so that the base material is exposed at the cut end surface, causing corrosion and malfunction or failure.

On the other hand, in the solder melt dipping method, it is difficult to form a solder film only on the outer leads when the semiconductor package is a FLAT type, that is, when the outer leads project in four directions. It was not easy to remove the liquid, and the solder adhered in a bridge shape between the outer leads. Further, it is difficult to control the film thickness of the solder melt that adheres to the outer leads, and the thickness of the solder film is uneven or too thick.

Further, the solder melt tends to form an oxide film on the surface and also contains a flux. If it adheres, it has an adverse effect on the wettability of the solder, so it is necessary to constantly circulate and jet the solder melt to filter it. Since the circulation / jet of the solder melt is conventionally performed by a pump, the device becomes large. In addition, the generated oxides and the like clog the pipes, which causes troubles, and cleaning and removal work for the troubles is troublesome.

Therefore, the present applicant previously developed a rotary solder coating method and device and applied for a patent (Japanese Patent Application No. 2-5709). This is to rotate the rotary solder bath around the central vertical axis, and to dip and attach the soldered outer package to the solder melt that has risen along the inner peripheral surface of the outer peripheral wall by centrifugal force,
The outer package to be soldered is also rotated so that the attached solder melt is spun off by centrifugal force to be thin and uniform, and solidified in that state.

As a result, the solder film on the outer leads of the soldered outer package can be made thin and uniform, and since the solder melt constantly circulates and the surface of the solder melt is always new, oxide films etc. are less likely to occur and high quality is achieved. It is now possible to form a solder film.

It is an object of the present invention to provide a method and apparatus for more efficiently supplying a solder melt and removing an oxide film in this rotary solder processing method.

Configuration of the Invention [Means for Solving the Problems] I The first method of removing a solder melt and supplying an oxide film and the like in the rotary solder processing method according to the present invention is the non-rotating outer solder bath (1). Then, rotate the doughnut-shaped rotary solder bath (2) around the central vertical axis (7),
The outer package (6) to be soldered is immersed in and adhered to the solder melt (5) rising along the inner peripheral surface of the outer peripheral wall (9) by centrifugal force, and the outer package (6) to be soldered is also rotated. Then, in the rotary solder treatment method in which the attached solder melt (5) is shaken off by centrifugal force to be thinly and uniformly solidified, the inner solder bath (2) is rotated by rotating the inner solder bath (2). The solder molten liquid (5) rising along the inner peripheral surface of the outer peripheral wall (9) is overflowed from the upper end of the outer peripheral wall (9) to the outer solder bath (1), and a filter (10 ) To remove oxides (15), and in the inner solder bath (2) where the solder melt (5) has decreased,
Solder melt replenishment hole (8) near the bottom of the solder bath (2)
From this, the solder melt (5) in the outer solder bath (1) is caused to flow in, and the solder melt (5) is circulated.

II The second method of removing the solder melt and supplying the oxide film by the rotary solder processing method according to the present invention is the same as the first method of supplying the solder melt and removing the oxide film. The solder melt (5) in the outer solder bath (1) after being overflowed from the inner solder bath (2) and filtered by the centrifugal force generated by the rotation is communicated with the outer solder bath (1) at a lower portion. The sub-filter (13) provided in the middle of overflowing again from the partition plate (11) installed upright
The oxide etc. (15) are removed again.

III. The third method of removing the solder melt and supplying the oxide film by the rotary solder processing method according to the present invention is the same as the first method of supplying the solder melt and removing the oxide film. Outer peripheral wall (9) Inner peripheral edge of upper end (14)
By making the inward dimension (t) variable, the thickness of the solder melt (5) rising along the inner peripheral surface of the outer peripheral wall (9) is adjusted.

IV The first of the solder melt supply and oxide film removing devices in the rotary solder processing method according to the present invention has a heating / heat retaining means (4) outside and puts the solder melt (5) inside. The non-rotating outer solder bath (1), the rotating inner solder bath (2) rotating in the outer solder bath (1), and the soldered outer package (6) are held, and the inner solder bath (2) is held. ) And a holding / rotating means (3) that rotates at substantially the same speed. The inner solder bath (2) is a donut shape with an upper opening, and the lower half of the inner solder bath (2) is the molten solder in the outer solder bath (1). (5) Immersed in the outer solder bath (1) and connected to the vertical axis (7) for rotating the inner solder bath standing at the center of the outer solder bath (1), and melted solder that communicates with the outer solder bath (1) near the bottom. A liquid replenishing hole (8) is provided, and an overflow molten liquid filter (10) is provided outside the outer peripheral wall (9) of the inner solder bath (2).

V The second solder melt supply / oxide film removing device in the rotary solder processing method according to the present invention is the same as the first solder melt supply / oxide film removing device, in which the outer solder bath (1) and the inner solder bath (1) A partition plate (11) that communicates with the lower hole (12) is erected between the outer wall (9) of the solder bath (2) and overflow melting also outside the partition plate (11). A liquid sub-filter (13) is provided.

VI Third aspect of the solder melt supply / oxide film removing device in the rotary solder processing method according to the present invention is the outer periphery of the inner solder bath (2) in the first solder melt supply / oxide film removing device. An inner peripheral edge portion (14) is variably provided at the upper end of the wall (9) for adjusting the thickness of the solder melt (5) rising along the inner peripheral surface of the outer peripheral wall (9). It is provided.

[Action]

The implementation state of the method and apparatus for supplying the solder melt and removing the oxide film in the rotary solder processing method according to the present invention having the above-described configuration is as follows.

I When the inner solder bath is stopped (see FIG. 2) The solder in the outer solder bath (1) whose outside has been heated by the heating / heat retaining means (4) is in a molten state. When the rotary type inner solder bath (2) is stopped, the solder melt (5) in the inner solder bath (2) and the outer solder bath (1) is discharged from the outer solder bath (1).
And the inner solder bath (2) communicate with each other through the molten solder replenishment hole (8) near the lower part of the inner solder bath (2), and the outer solder bath (1) also communicates with the lower part of the partition plate (11). . Therefore, the solder melt (5) is collected in the lower half of each part in both tanks (1) and (2) and has the same liquid level (see FIG. 2).

II When the inner solder bath is rotating (See Fig. 1 and Fig.) When the rotary type inner solder bath (2) is rotating, the inner solder bath (2)
The molten solder liquid (5) inside rises along the inner peripheral surface of the outer peripheral wall (9) of the inner solder bath (2) due to the centrifugal force caused by the rotation thereof.

The solder melt (5) rising as described above overflows from the upper end of the outer peripheral wall (9), so that the oxide (15) is continuously filtered and removed by the filter (10) provided on the way. And enters the outer solder bath (1) as a solder melt of eutectic solder containing no impurities.

Further, due to the overflow, the solder melt (5) in the inner solder bath (2) gradually decreases, but the inner solder bath (2)
Since the solder melt liquid replenishment hole (8) communicating with the outer solder bath (1) is provided near the lower part, the solder melt liquid (5) in the outer solder bath (1) is continuously replenished. Become.

In addition, as the solder sheath for the solder sheath (6), the solder sheath (6) is brought into the inner solder bath (2) in the above state, and the solder sheath (3) is held by the holding / rotating means (3). 6) is moved in the outer peripheral direction while rotating at the same speed as the inner solder bath (2) to attach the rising solder melt (5) to the outer lead (16), and by centrifugal force due to the subsequent rotation, The attached solder melt (5) may be made thin and uniform, and then solidified in that state.

III In the case where a partition plate that communicates with the lower part of the outer solder tank is erected upright, and a filter for the overflow melt is also provided outside the partition plate. When the inner solder tank (2) rotates, its rotational force is A centrifugal force also acts on the solder melt (5) in the bath (1) to cause the partition plate (11) in the outer solder bath (1) and the outer peripheral wall (9) of the inner solder bath (2). In the meantime, the solder melt (5) rises along the partition plate (11).

Therefore, the rising solder melt (5) overflows from the upper end of the partition plate (11) and flows down to the outside of the partition plate (11). A filter (1
Solder melt (5) which has been filtered once by (0)
Here again, the oxides and the like (15) are filtered and removed again.

Then, the solder melt (5), which became more eutectic solder with no impurities, was pushed from the through hole (12) in the lower part of the partition plate (11) toward the center of the outer solder bath (1), and was described in II above. As described above, the solder is supplied continuously into the inner solder bath (2) through the solder melt supply hole (8) near the lower part of the inner solder bath (2).

In the case where the inner peripheral edge is provided at the upper end of the outer peripheral wall of the IV inner solder bath so that the inner dimension can be varied. When the inner solder bath (2) is rotated, the solder melt (5) is rotated by the centrifugal force as described above. It rises along the inner peripheral surface of the wall (9), but even if the thickness of the solder melt (5) becomes thicker than the inward dimension (t) of the inner peripheral edge portion (14), the excess amount overflows. Will be done.

Therefore, the thickness of the solder melt (5) rising along the inner peripheral surface of the outer peripheral wall (1) is the thickness (t) of the inner peripheral edge portion (14).
It's just something. Therefore, the amount of the solder melt (5) attached to the outer leads (16) can be adjusted according to the length of the outer leads (16) and other differences in the outer package (6) to be soldered.

〔Example〕

In the embodiment shown in FIGS. 1 to 3, the fixed type outer solder bath (1) is surrounded by a heating / heat retaining means (4), and a solder melt (5) is placed inside. A lid plate (17) that can be opened on both sides is provided in the upper part, and a cylindrical part (18) through which the vertical axis (7) for rotating the inner solder bath can be inserted is provided upright from the central lower part. is there. The shape of the outer solder bath (1) may be round or square.

The rotating inner solder bath (2) has a donut shape with an upper opening,
The lower half is immersed in the solder melt (5) in the outer solder bath (1), and by the horizontal support plate (19) at the center,
It is connected to the vertical axis (7) for rotating the inner solder bath, which is inserted through the cylindrical portion (18) at the center of the outer solder bath (1). The inner solder bath rotating vertical axis (7) is cylindrical and has a lower portion connected to the inner solder bath rotating motor (20) via a belt (20).

The outer peripheral wall (9) of the inner solder bath (2) is a portion where the solder melt (5) whose upper end has risen overflows, but outside the outer peripheral wall (9), the overflow melt is formed. A mesh-shaped filter (10) for filtering and removing oxides (15) is provided. The filter (10) is separate from the inner solder bath (2) and is fixed in the outer solder bath (1).

The inner solder bath (2) is located between the outer solder bath (1) and the inner solder bath (2).
Hole (8) for replenishing solder melt near the bottom of the inner peripheral wall (22)
Is formed so that both tanks (1) and (2) communicate with each other.

Further, an inner peripheral edge portion (14) is variably provided on the upper end portion of the outer peripheral wall (9) of the inner solder bath (2) for adjusting the thickness of the rising solder melt (5). It is provided. In order to make the inward dimension (t) variable, here, the annular inner peripheral edge portion (14) having a different inner diameter is connected to the outer peripheral wall (9).
It is replaceably attached to the upper end.

Further, a partition plate (11) whose lower portion communicates with a through hole (12) is erected between the outer peripheral wall (9) of the outer solder bath (1) and the inner solder bath (2), and the partition plate ( A sub-filter (13) for overflow melt is also provided outside of 11).

In the lower part of the lid plate (17) above the outer solder bath (1), the overflowing solder melt (5) is filled with the inner solder bath (2).
Plate (23) leading to the filter (10) outside the outer peripheral wall (9)
Is provided.

The holding / rotating means (3) is connected to a holding jig (25) whose arms extend outside while holding the parts other than the outer leads (16) of the outer package (6) to be soldered at the upper part, and the holding jig at the lower part. Holding jig rotation axis (24) connected to rotation motor (26)
Consists of. The holding jig rotating vertical axis (24) is inserted into the inner solder bath rotating vertical axis (7) and can rotate at substantially the same speed as the inner solder bath rotating vertical axis (24). There is. The holding / rotating means (3) can separate the lower half part and the upper half part at the central part of the holding jig rotating vertical axis (26) so that the holding jig (2) can be connected to the inner solder bath (2). ) It is possible to move in and out.

EFFECTS OF THE INVENTION As is apparent from the above, the method and the device for replenishing the solder melt and the oxide film in the rotary solder treatment method according to the present invention are the replenishment of the solder melt and the oxide film in the rotary solder treatment method. Can be removed very efficiently.

I First, regarding the filtration of oxides or the like of the solder melt, in the present invention, the rotating inner solder bath is rotated in the fixed outer solder bath,
The centrifugal force causes the molten solder that has risen along the inner peripheral surface of the outer peripheral wall of the inner solder tank to overflow from the upper end of the outer peripheral wall, and is filtered by a filter to be returned to the outer solder tank.

Therefore, the solder melt can be continuously and automatically circulated to remove oxides and the like without increasing the size by using a pump as in the conventional case, and the solder melt of eutectic solder without impurities can be enhanced by the solder melt. It is possible to perform quality solder exterior processing.

II Next, regarding the replenishment of the solder melt to the inner solder bath for solder exterior coating, in the present invention, the inner solder bath is immersed in the outer solder bath containing a large amount of the solder melt in the lower part, The inner solder bath is rotated.

Therefore, even if the solder melt in the inner solder bath decreases due to the overflow, the filtered solder melt can be continuously and automatically replenished from the outer solder bath to the inner solder bath accordingly. You can

Further, regarding the filtration of oxides of the solder melt, in the illustrated embodiment of the present invention, a partition plate communicating with the lower part of the outer solder tank is erected, and a filter for the overflow melt is also provided outside the partition plate. It is provided. As a result, the molten solder liquid between the partition plate and the outer peripheral wall of the inner solder tank rises along the partition plate due to the rotation of the inner solder bath and overflows, and is continuously and automatically filtered.

Therefore, the solder melt becomes eutectic solder with less impurities, and high-quality solder coating processing can be performed.

In addition, in the illustrated embodiment of the present invention, the inner peripheral edge portion having a variable inward dimension is provided at the upper end portion of the outer peripheral wall of the inner solder bath. As a result, when the solder melt rises along the inner peripheral surface of the outer peripheral wall due to the rotation of the inner solder bath, the solder melt larger than the dimension of the inner peripheral edge overflows.

Therefore, by changing the inward dimension of the inner peripheral edge portion, the thickness of the solder melt that rises in the inner solder bath can be adjusted, and the amount of the solder melt that adheres to the package to be soldered can be adjusted.

[Brief description of drawings]

FIG. 1 shows an example of an apparatus for carrying out a method for replenishing a solder melt and an oxide removing method in a rotary solder processing method according to the present invention, and FIG. 1 shows an entire apparatus in an operating state in which an inner solder bath and a holding jig rotate. FIG. 2 is a vertical sectional front view of a main portion when the inner solder bath and the holding jig are stopped, and FIG. 3 is a main portion when the inner solder bath and the holding jig are rotated. FIG. Drawing reference numeral (1) ... outer solder bath, (2) ... inner solder bath (3) ... holding / rotating means, (4) ... heating and heat retaining means (5) ... solder melt, (6) …… Solder to be soldered (7) …… Rotation axis for inner solder bath rotation, (8) …… Supply hole (9) …… Outer wall, (10) …… Filter (11) …… Partition plate, ( 12) ...... through hole (13) ...... sub-filter, (14) …… inner peripheral edge (15) …… oxide, etc. (16) …… outer lead (17) …… cover plate, (18) …… Cylindrical part (19) …… Horizontal support plate, (20) …… Motor (21) …… Belt, (22) …… Inner peripheral wall (23) …… Guide plate, (24) …… Vertical axis (25 ) …… Holding jig, (26) …… Motor (t) …… Thickness

Claims (6)

[Claims] 1. A non-rotating outer solder bath (1), wherein a doughnut-shaped inner rotating solder bath (2) is rotated around a central vertical axis (7) and centrifugal force is applied to the outer peripheral wall ( 9) The outer packaged object (6) to be soldered is immersed in and adhered to the molten solder liquid (5) rising along the inner peripheral surface of 9), and the outer packaged object (6) to be soldered is also rotated to melt the attached solder. In a rotary soldering method in which the liquid (5) is shaken off by centrifugal force to be thinly and uniformly solidified, the outer peripheral wall (9) of the inner solder bath (2) is rotated by rotating the inner solder bath (2). The solder melt (5) rising along the inner peripheral surface overflows from the upper end of the outer peripheral wall (9) to the outer solder bath (1), and oxides etc. are generated by a filter (10) provided on the way. (15) is removed, and in the inner solder bath (2) where the solder melt (5) is reduced,
Solder melt replenishment hole (8) near the bottom of the solder bath (2)
From the above, the solder melt solution (5) in the outer solder bath (1) is caused to flow in so that the solder melt solution (5) is circulated. 2. The solder melt (5) in the outer solder bath (1) after being overflowed from the inner solder bath (2) and filtered by centrifugal force generated by the rotation of the inner solder bath (2) Overflow again from the partition plate (11) erected so as to communicate with the lower part in the solder bath (1), and remove the oxides (15) again by the sub-filter (13) provided in the middle. The method for replenishing a solder melt and also removing an oxide film by the rotary solder processing method according to claim 1. 3. An inner peripheral surface of an outer peripheral wall (9), wherein an inner peripheral edge portion (14) of an upper end portion of the outer peripheral wall (9) of the inner solder bath (2) has a variable inward dimension (t). The solder melt replenishment and oxide film removal method according to claim 1, wherein the thickness of the solder melt (5) rising along the line is adjusted. 4. A non-rotating outer solder bath (1) having a heating / heat-retaining means (4) outside and containing a solder melt (5) inside and an outer solder bath (1). Holding and rotating means (3) for holding the rotating inner solder bath (2) and the outer package to be soldered (6) and rotating at substantially the same speed as the inner solder bath (2).
The inner solder bath (2) has a donut shape with an upper opening, and the lower half is immersed in the solder melt (5) in the outer solder bath (1) to form the outer solder bath (1). It is connected to a vertical axis (7) for rotating the inner solder bath which is erected at the center, and a solder melt supply hole (8) communicating with the outer solder bath (1) is provided near the lower part, and the inner solder bath (7) A solder melt replenishment and oxide film removal device by a rotary solder treatment method, wherein an overflow melt filter (10) is provided outside the outer peripheral wall (9). 5. A partition plate (11) communicating with a lower through hole (12) is erected between the outer solder bath (1) and the outer peripheral wall (9) of the inner solder bath (2), The solder melt replenishment and oxide film removal device in the rotary solder processing method according to claim 1, further comprising an overflow melt subfilter (13) provided outside the partition plate (11). 6. An inner dimension for adjusting the thickness of the solder melt (5) rising along the inner peripheral surface of the outer peripheral wall (9) at the upper end of the outer peripheral wall (9) of the inner solder bath (2). The solder melt replenishing and oxide film removing device in the rotary solder processing method according to claim 1, wherein the inner peripheral edge portion (14) is provided so that (t) is variable.