JPH08306847A - Solder coating equipment of shaped ic - Google Patents

Abstract

PURPOSE: To form a uniform solder coating film on a lead part without generating bridges, by a method wherein the lead part of a shaped IC is fitted in a processing chamber, solder jet sent by a pump is made to jet uniformly from four sides by a solder block, and the shaped IC is horizontally retained. CONSTITUTION: A process chamber 16 capable of maintaining a low oxygen concentration gas atmosphere is linked with a solder vessel 3 receiving fused solder 28. A process chamber wall 17 is installed penetrating a lid 15 for isolation from the outer atmosphere. The lead part of a shaped IC 27 is fitted in the process chamber 16. Solder jet sent by a pump 25 is made to uniformly jet from four sides by a solder block 22 having slits. The shaped IC 27 is horizontally retained by a two-direction conveying equipment. Thereby, a uniform solder coating film is formed on the lead part without generating bridges.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder coating device for a shaped IC.

[0002]

2. Description of the Related Art In order to improve the electrical connection between a semiconductor lead and a printed circuit board when mounting electronic parts on a board and to improve the efficiency of mounting work, solder is previously attached to the lead parts of the electronic parts. A film is formed, and a solder dipping method (immersion) is one method of forming the solder film. This solder film formation is also required for shaped ICs. On the other hand, on the other hand, the number of pins and the pitch of the package have been increasing along with the high integration of electronic parts in recent years, and the solder dipping method has made it possible to obtain a uniform pitch without causing a bridge in precision electronic parts such as ICs. Since it is technically difficult to form a solder coating film, the introduction of an automatic solder coating forming apparatus to an IC production line is almost zero.

In an example of forming a solder coating film by the dip method which is currently used as shown in FIG. 8, the oxide generated on the surface of the molten solder (B) in the solder bath (A) is scraped off by a scraper (C). The lead portion of the shaped IC (D) is immersed in the solder surface portion in a low-oxidation state that appears for a while. Thereafter, the immersed lead portion is gently pulled up by the carrier device (E) to form a solder coating.

Further, Japanese Patent Application Laid-Open No. 6-899 filed previously.
59 (FIG. 9) is one of the few automatic machines that currently forms a solder coating on a shaped IC. Figure 9
In the conventional example, the mount (G) is provided vertically on the main body (F), and the moving device (H) is attached to the mount (G). This moving device (H) is provided so that the X-axis table (J) can be moved by the motor (I), and further the Y-axis table (K) can be moved, and the shaped IC is formed by the vertical chuck (L) provided at the tip.
(P) can be held.

Further, a shaped IC is formed in a flow-down groove (not shown) provided in a solder block (O) for supplying molten solder with a pump (N) provided in a solder bath (M) installed on the apparatus body (F). (P) is dipped and solder coated.

[0006]

As described above, although there is a strong demand for forming a solder coating on the leads of a shaped IC,
It has not been widely put to practical use. The reason is
Although several methods have been invented, it has been mentioned that they have not yet produced satisfactory results in terms of cost and quality. For example, in the solder dipping device shown in FIG. 8, the oxide on the surface of the molten solder is removed by the scraper (C), and then the lead portion of the shaped IC (D) is immersed. However, in this state, the soldering device is always exposed to the atmosphere, the surface of the molten solder is oxidized by oxygen in the atmosphere, and the oxidized solder adheres to the leads, causing a bridge. .

Even if the entire apparatus is covered with a cover to realize an environment of low oxygen concentration atmosphere, highly integrated and narrow-pitch ICs (for example, lead pitch of 0.3 mm, etc.), which are becoming the mainstream in recent years, are being used. ), Bridge formation is unavoidable due to the action of the surface tension of the molten solder.

Next, Japanese Patent Application Laid-Open No. 6-89 filed previously.
959 (Fig. 9) is one of the few examples that can be applied to the solder coat of a narrow pitch IC at present, but if the solder coat work is continuously performed, the oxide of the solder is accumulated on the solder block, which causes Sometimes caused a bridge. Further, it is difficult to control the solder thickness due to its principle, and in particular, a phenomenon in which a solder pool occurs due to surface tension inside the bent portion of the lead portion was observed. Further, due to its structure, it has a drawback that only one row of leads arranged on the same side of the IC mold can be processed by one operation. In case of QFP,
Since the leads are lined up on each of the four sides of the mold, this apparatus must be processed four times, which is a major limitation in reducing the processing time.

Therefore, the present invention solves these problems found in the conventional apparatus and not only forms a uniform solder coating on the leads without bridging, but also maintains stable operation in continuous operation. Moreover, it is possible to provide a method and an apparatus for realizing a reduction in working time by enabling processing of all one IC lead portion in one step.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention connects a processing chamber capable of maintaining a low oxygen concentration gas atmosphere to a solder tank containing molten solder, and Solder coating of shaped IC with a solder block having a slit into which the lead portion of the shaped IC is fitted and which allows a solder jet flow fed by a pump to be uniformly jetted from four sides, and a conveying means for holding the shaped IC horizontally. Configure the device.

Further, a solder coating apparatus for a shaped IC is provided in which a gas injection nozzle having a slit for continuously injecting a high temperature gas and a cooling gas is installed in the lead portion of the shaped IC in the processing chamber.

Further, a solder coating device of a shaped IC in which a horn for ultrasonic vibration is attached to a solder block is constructed.

[0013]

The present invention is configured as described above, and since the solder coating is performed inside the processing chamber where the oxygen concentration is kept low, no oxide is generated on the solder jet flow and the oxide adheres. It is possible to prevent the bridge caused by. In the case of molten solder, it is known that the wettability of solder is better when it is in a normal atmosphere, that is, in a low oxygen concentration environment than when there is an oxide on the surface. Quality such as thickness and surface condition is improved.

On the other hand, the shaped IC which is held horizontally by the transfer device is immersed in a solder jet which is uniformly jetted from four sides on a solder block provided inside the processing chamber. Is contained inside the slit of the solder block, and the inner wall of the slit and the lead are kept in close proximity to each other, which has the effect of preventing more than the necessary amount of solder from adhering to the lead, preventing bridges and even soldering. Allows for coats. Further, the structure in which the horizontally held work is immersed in the molten solder by using the solder block enables all the lead portions of one IC to be solder-coated in one step, which shortens the processing time.

In the case where a gas injection nozzle is attached to the above-mentioned device, after the lead portion of the shaped IC is solder-coated, a high temperature gas is further blown from a certain direction to form once. While melting the solder coating, collect the solder partially due to the force of the gas flow,
By continuously injecting low-temperature gas, the solder coating can be solidified while the solder is partially biased. This makes it possible to increase the thickness of the solder coating only on an arbitrary part of the lead portion.

Further, when an ultrasonic vibration horn is attached to the above apparatus, the solder block in the processing chamber is ultrasonically vibrated, so that the molten solder is cavitated by the cavitation action when the ultrasonic wave propagates in the molten solder. Will hit the coated surface of the lead part strongly. Therefore, even if an oxide film is formed on a part or all of the target lead surface, the molten solder is surely brought into contact with the lead portion, and a dense and uniform solder coating is applied. Also, due to the action of the cavitation, a solder coat that does not require flux can be realized.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5. As shown in the front view of FIG. The device 3, the solder bath 4, the ultrasonic cleaning device 5, and the drying device 6 are fixed to each other, and an IC holding arm 8 is attached to a pedestal 7 fixed vertically to the device main body 1.
The two-way transport device 9 including is fixed.

As shown in FIGS. 1 and 2, the bidirectional transfer device 9 has a movable member 11 screwed into a rotary screw rod 10 provided so as to be normally rotated in the horizontal direction, and upper and lower guide grooves 12, 12 are provided.
A guide rod (not shown) can be fitted in the ′ to move the moving member 11 left and right without rotating. An elevating member 13 is attached to the moving member 11 so as to be able to move up and down, and an IC holding arm 8 provided with a suction pad 14 is attached to the elevating member 13.

As shown in FIG. 3, the upper surface of the solder bath 3 can be sealed with a lid 15, and a processing chamber 16 communicating with the solder bath 3 is formed at a part of the solder bath 3 and insulated from the outside air. Thus, the processing chamber wall 17 is provided so as to penetrate the lid 15.

On the upper surface of the processing chamber wall 17, the work entrance / exit 1
8 and a shutter 19 for closing it. Further, a pipe 20 for introducing gas is provided from the side surface of the processing chamber wall 17 so that the inert gas heated by the gas heating heater 21 can be introduced into the processing chamber 16. On the other hand, in the processing chamber 16, a solder block 2 having a rectangular cross section is provided.
2 is fixed to the block base 23, the block base 23 is connected to the solder pump 25 by the support plate 24, and the slit 22 'is provided so as to supply the flow rate-controlled molten solder to the solder block 22 (see FIG. 5). It is provided on the peripheral surface.

As shown in FIGS. 4 and 5, the solder block 22 is provided with slits 22 'for uniformly ejecting the molten solder 28 on four sides and a space 22 "in the middle to form a molded portion of the shaped IC 27. The space portion 22 ″ is communicated with the solder bath 3 so as not to hit the solder block 22 so that molten solder does not accumulate and thermal shock due to contact of the mold portion is avoided.

In FIG. 3, 26 is a motor for driving the solder pump 25, 28 is molten solder, and 29 is a heater.

The first embodiment is constructed as described above. First, the IC holding arm 8 is moved by the bidirectional transport device 9, and the IC receiving table 2 is moved by the suction pad 14 at the tip of the IC holding arm 8. Shaped IC2 placed on top of
7 is vacuum-adsorbed and held. Next, the shaped IC 27 is carried to the automatic flux applying device 3 by the bidirectional carrying device 9,
Liquid flux is applied to the lead portion of the shaped IC 27, and after the completion, the shaped IC 27 is moved to above the solder bath 3. On the other hand, inside the processing chamber wall 17, a uniform and stable solder jet is formed on the solder block 22 supplied with the molten solder 28 controlled by the solder pump 25. Further, since the inert gas heated to about 300 ° C. is introduced by the external gas heater 21, the processing chamber 1
No. 6 was kept in a low oxygen concentration state (oxygen concentration of 400 ppm or less), and no phenomenon of oxide generation on the surface of the molten solder 28 was observed.

Next, by the bidirectional transport device 9, the shaped I
C27 is lowered in the vertical direction, and the shaped IC 27 is carried into the processing chamber 16 from the work entrance / exit 18 with the shutter 19 opened. The work entrance 18 closes the shutter 19 after the shaped IC 27 has passed. Further, the IC holding arm 8 can move up and down even when the shutter 19 is closed, and after the shaped IC 27 is loaded into the processing chamber 16, the shutter 19 is closed promptly.
It is possible to maintain a low oxygen concentration atmosphere.

Next, the shaped IC 27 is further lowered, and slits 22 'provided on the four sides of the solder block 22 are provided.
It is immersed in the upper solder jet (see Fig. 5). At this time, as shown in the cross-sectional view of FIG. 5, the lead portion of the shaped IC 27 is 1 mm / sec to 5 mm / from the solder block 22.
When pulled up at a speed of about sec, a bridge is not formed in the lead portion of the shaped IC lead alem 27,
A uniform solder coating can be formed.

After the above solder coating process is completed, the shaped IC 27 is carried out of the processing chamber 16, cleaned by the ultrasonic cleaning device 5, dried by the drying device 20 and conveyed to the IC receiving table 2.

Next, a second embodiment will be described with reference to FIG. 6. In this embodiment, a gas injection nozzle 30 for controlling the solder thickness in the first embodiment is attached to the processing chamber 16. . The gas injection nozzle 30 is provided in the shape of a circular ring, and a slit 32 having a fine slit width is provided obliquely downward at the lower end of a circular reservoir 31 at the center. At the same time, the conduit 33 and the nozzle heater 3 are connected to the lead portion.
The high-temperature nitrogen gas heated by 4 can be injected at high speed. Since the configuration of the device other than that is the same as that of the first embodiment, the same reference numerals are given and the description thereof is omitted.

In this embodiment, the shaped IC 27 is carried into the processing chamber 16 by the same method as in the first embodiment, and the solder block 2
Solder coating is applied on 2. Then, after removing the shaped IC 27 from the solder jet, the shaped IC 27
Are carried to the gas injection position of the gas injection nozzle 30 mounted above the solder block 22. At this gas injection position, the nitrogen gas flow injected at an angle of 45 degrees obliquely downward by the slit 32 of the gas injection nozzle 30 is shaped IC
It is set to directly hit the lead part.

Here, the slit 3 of the gas injection nozzle 30
Nitrogen gas with a temperature higher than 2 is injected, and the injected nitrogen gas melts the solder coating covering the lead portion of the shaped IC 27, and the gas is blown down diagonally to the lower portion of the lead portion. You can collect solder pools. At this time, if the power of the gas injection nozzle heater 34 is turned off while the gas is still being ejected, the temperature of the ejected gas is lowered, and the melted solder on the shaped IC is also transferred to the T portion of the lead portion. It is possible to coagulate in the state of being collected. After the solder on the shaped IC is solidified by the above-mentioned action, the nitrogen gas injection from the gas injection nozzle 30 is stopped, and thereafter, the operation similar to that of the first embodiment is performed to complete the shaped IC2.
7 is carried out from the processing chamber 16 and washed and dried.

Next, the third embodiment will be described in detail with reference to FIG. 7. In this embodiment, an ultrasonic vibration horn is attached to the solder block 22. That is, the horn 35 is fixed to the side surface of the solder block 22, and the heat insulating collar 36
The ultrasonic transducer 39 is fixed with the cone 37 sandwiched therebetween and the heat insulating collar 38 sandwiched therewith. The flange portion 40 of the cone 37 is fixed to the processing chamber wall 17. It supports the ultrasonic vibration device part, and the cone 37 and the ultrasonic vibrator 39 are covered with a cover 41. Others are the same as those in the first embodiment, and therefore, the same reference numerals are given and the description thereof is omitted.

In this embodiment, as in the first embodiment,
First, the shaped IC 27 is carried by the bidirectional carrier 9 to the processing chamber 16 kept in a low oxygen concentration state. However, at this time, the flux applying work by the automatic flux applying apparatus 3 is not performed. Shaped IC 27 carried to processing room 16
Is immersed in the solder jet flow on the solder block 22. At this time, the solder block 22 is vibrated by the action of the ultrasonic transducer 39, and the molten solder jetted into the block causes cavitation. By immersing the lead portion of the shaped IC 27 in this molten solder, soldering can be performed without flux. Thereafter, the shaped IC 2 is formed in the same manner as in the first embodiment.
7 is taken out of the solder jet stream and carried out of the processing chamber 16. However, since no flux is used in this embodiment, cleaning and drying operations are unnecessary.

[0032]

Industrial Applicability The present invention has the above-mentioned structure and operation, and by performing the soldering work in a gas atmosphere, a clean solder coating free of oxide adhesion can be achieved, and the solder block can be formed. By using it, the IC can be processed simultaneously in one process without generating a bridge.
You can solder coat the leads on all sides. At this time, since the mold portion of the IC is not directly immersed in the molten solder, thermal shock can be avoided. In addition, by controlling the flow rate and the pulling rate of the solder when pulled up from the solder block, it is possible not only to prevent the occurrence of bridges, but also to control the solder thickness and improve quality such as uniformity. .

After the solder coating, a high temperature gas is sprayed on the solder coating surface, whereby the partial solder thickness can be controlled.

Since the solder block is ultrasonically vibrated, it is possible to perform soldering work without using flux.
Flux application, washing and drying steps can be omitted, and a more economical and efficient device can be constructed.

[0035]

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of a solder coating device for a shaped IC according to the present invention.

FIG. 2 is a side view thereof.

FIG. 3 is a vertical cross-sectional view showing a processing chamber and a solder bath.

FIG. 4 is a perspective view of a solder block.

FIG. 5 is a sectional view of a solder block.

FIG. 6 is a vertical cross-sectional view of the second embodiment.

FIG. 7 is a vertical sectional front view of the third embodiment.

FIG. 8 is a perspective view of a conventional device.

FIG. 9 is a front view of another conventional example.

[Explanation of symbols]

 1 Device Main Body 2 IC Receiving Table 3 Automatic Flux Coating Device 4 Solder Tank 5 Ultrasonic Cleaning Device 6 Drying Device 7 Stand 8 IC Holding Arm 9 Two-Way Transfer Device 10 Rotating Screw Rod 11 Moving Member 12 Guide Groove 12 'Guide Groove 13 Lifting Member 14 Adsorption pad 15 Lid 16 Processing chamber 17 Processing chamber wall 18 Work inlet / outlet 19 Shatter 20 Pipe 21 Gas heating heater 22 Solder block 22 'Frit 22 "Space 23 Block base 24 Support plate 25 Solder pump 26 Motor 27 Preformed IC 28 Melt Solder 29 Motor 30 Gas Injection Nozzle 31 Reservoir 32 Slit 33 Conduit 34 Nozzle Heater 35 Horn 36 Insulation Collar 37 Cone 38 Insulation Collar 39 Ultrasonic Transducer 40 Flange 41 Cover A Solder Tank B Melting Solder Da C scraper D the shaped IC F apparatus main body G gantry H mobile device I motor J X-axis table K Y axis table L vacuum chuck M solder bath N pump O solder blocks P the shaped IC

Claims (3)

[Claims] 1. A solder bath containing molten solder is connected to a processing chamber capable of maintaining a low oxygen concentration gas atmosphere, and a lead portion of a shaped IC is inserted into the processing chamber and pumped. A solder coating device for a shaped IC, comprising: a solder block having slits for uniformly jetting the solder jet from four sides; and a conveying means for horizontally holding the shaped IC. 2. A shaped injection nozzle according to claim 1, wherein a gas injection nozzle having a slit for continuously injecting a high temperature gas and a cooling gas into the lead portion of the shaped IC is installed in the processing chamber. IC solder coating equipment. 3. The solder coating device for a shaped IC according to claim 1, wherein an ultrasonic vibration horn is attached to the solder block.