JPH0435909B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an electrode processing method for semiconductor devices such as DIP (dual in package), which is a type of electronic component that contributes to the reduction in weight, thickness, and size of electronic devices. It is something.

BACKGROUND ART Conventionally, this type of semiconductor device has had a configuration as shown in FIG.

FIG. 3 shows, as an example, a plastic chip carrier (hereinafter referred to as PLCC) type semiconductor device, in which FIG. 3A is a perspective view and FIG. 3B is a sectional view. In the figure, 1 is a silicon (Si) pellet, 2 is a bonding wire, 3 is an electrode for leading to the outside, and 4 is a resin. Here, the external lead-out electrode 3 is made of a copper (Cu)-based material with a nickel (Ni) base plating, and solder (Sn-Pb-based alloy) is applied on top of the nickel (Ni) base plating.
It has been plated.

FIG. 4 shows a perspective view of a dual inline package (hereinafter referred to as DIP) type semiconductor device as an example. The external lead electrode 3 in this DIP type semiconductor device is made of a copper (Cu) or iron-nickel (Fe-Ni) material plated with solder (Sn-Pb alloy). At this time, in the case of copper (Cu) based materials, nickel (Ni) plating may be applied as the base plating. In addition, solder (Sn
-Pb-based alloy) Lead (Pb) plating is sometimes used instead of plating.

In this way, conventional semiconductor devices have a low melting point metal plating film or a low melting point alloy plating film (hereinafter collectively referred to as low melting point metal plating film) on the outermost layer of the electrode part, and in some cases, As a base layer, a high melting point metal film or a high melting point alloy film made of a material having a higher melting point than the above-mentioned low melting point metal plating film and having good affinity with the low melting point metal plating film (hereinafter, these are collectively referred to as the high melting point metal film) ) is formed.

In a semiconductor device having such a conventional configuration, the outermost layer of the electrode portion is composed of a low melting point metal plating film,
Its surface is rough and has a very large surface area. For this reason, these films tend to absorb foreign matter and adsorb gases, and if stored for a long period of time, the electrode surface will undergo chemical changes such as oxidation, resulting in poor soldering when soldering to a printed circuit board. The problem was that there was a high possibility that the In addition, when the low melting point metal plating film is made of gloss plating to make the surface smooth, it has the fatal drawback of poor solderability because it contains impurities (organic substances). There is.

Now, as an electrode treatment method for smoothing the low melting point metal plating film, which has a rough surface as described above, an atmospheric furnace, an infrared furnace, a hot air furnace, a hot plate, etc. are used. A method using a heating electrode treatment method or a vapor phase soldering method (VPS method) is known. Among them, as an example, a method for processing electrodes of a semiconductor device using an infrared heater will be described below.

FIG. 5 shows a schematic diagram of an apparatus for carrying out the electrode processing method using this infrared heater.

In FIG. 5, 5 is a semiconductor device having a structure as shown in FIG. 3 or 4, 6 is a semiconductor device alignment machine, 7 is a flux coating machine, 8 is an infrared heater, 9 is a cooler, 10 11 is a belt drive unit; 12 is an electrode processing device stand; 13 is a semiconductor device conveyor belt;
is a belt washer.

The process of melting the low melting point metal plating film on the electrode portion of the semiconductor device consists of five steps: aligning the semiconductor device, applying flux, heating and melting, cooling and solidifying, and removing the semiconductor device.
That is, the semiconductor device aligning machine 6 is placed on the semiconductor device conveying belt 13 conveyed by the belt driving section 11.
After applying flux to the semiconductor device 5 in the next step, the electrode portion to which the flux has been applied is heated and melted using a tunnel-type infrared heater 8, and then the molten portion is transferred to a cooler 9. After that, the electrode-processed semiconductor device 5 is taken out by the electrode-processed semiconductor device take-out machine 10. Further, after the semiconductor device conveying belt 13 is cleaned by a belt washer 14, the semiconductor devices 5 are supplied again.

Problems to be Solved by the Invention In such a conventional electrode processing method, independent equipment is required for each process, and since the semiconductor device transport belt becomes contaminated with flux, a cleaning device must be installed. In addition, the equipment has to be larger, and the timing between each equipment has to be adjusted (the transfer speed of semiconductor devices transported by a conveyor belt, the timing of flux application and semiconductor device removal). to synchronize),
The basic problem was that it required precision equipment.

Problems with the above-described electrode processing method are listed below.

When the electrode parts of semiconductor devices are melted, the individual semiconductor devices must be aligned at intervals so that the electrode parts of each semiconductor device do not stick together, and this is a major factor that hinders mass production. .

Since the metal is heated and melted in air, flux is required to prevent oxidation of the molten metal surface.

Since flux is used, the flux is heated and burned into the semiconductor device, making it difficult to clean the semiconductor device.

Since the heating section is a tunnel type, air can move in and out freely, making it difficult to stabilize the temperature.

Since the conveyor belt is also heated at the same time, it takes time to heat and cool it, requiring a very long furnace and, moreover, a cooler for rapid cooling.

Since flux adheres to the conveyor belt and causes equipment failure, the conveyor belt must be cleaned.

Looking at the entire equipment, there are many mechanically moving parts, and flux is used on top of them, so
Flux adheres to moving parts of equipment, causing breakdowns and reducing equipment operating rates. As described above, the electrode processing method using the infrared heater shown in FIG. 5 has many problems, and there is a strong demand for improvement.

Further, the other electrode processing methods described above have problems similar to the electrode processing method using the infrared heater to a greater or lesser extent. And the dimensions of the above PLCC etc. are
For example, in an 18-pin rectangular PLCC type semiconductor device,
Due to the small size of 8.31 mm x 11.86 mm, and as mentioned above, the conventionally known electrode processing methods have many problems, so current semiconductor devices are The reality is that almost no treatment is done to make the surface of the part smooth.

The present invention solves the above-mentioned problems with the electrode portion of a semiconductor device, reduces the surface area of the electrode portion of the semiconductor device, and smooths it, thereby improving solder wettability and providing reliable soldering for long-term storage. The primary purpose is to improve sexual performance.
A second object of the present invention is to solve the problems of conventionally known electrode processing methods,
By eliminating mechanically moving parts, even if semiconductor devices are thrown in without being aligned, the electrode parts of each semiconductor device can be melted without touching each other during melting, and the melting temperature can also be precisely controlled. The object of the present invention is to process electrodes of semiconductor devices without using flux and with good mass productivity.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention includes placing a high boiling point liquid such as oil in a cylindrical container and creating a temperature gradient in the high boiling point liquid in the container. A semiconductor device holding a low melting point metal film (or a low melting point alloy film) on an electrode is moved from the high temperature side of the high boiling point liquid to the low temperature side of the high boiling point liquid in the container. A melting point metal film (or a low melting point alloy film) is melted, cooled in a low temperature section, and the melted section is solidified. In addition, as a preferred embodiment,
As the high boiling point liquid, any one of natural vegetable oil, natural animal oil, natural mineral oil, synthetic silicone oil, or glycerin is used. Furthermore, the low-melting point metal film (low-melting point alloy film) is composed of an electroplated film or a chemically plated film.

Effect According to this configuration, the low melting point metal film (low melting point alloy film) is melted on the high temperature side of the high boiling point liquid in the container and cooled on the low temperature side, so surface tension acts during melting and the surface area increases. By cooling in this state, the surface area becomes extremely small compared to that of a low melting point metal film (low melting point alloy film) formed by plating, etc., and the surface is also smooth. As a result, adhesion of foreign substances and gas adsorption during storage are extremely reduced. Additionally, since foreign substances and gases adsorbed or occluded on the surface or inside the recesses are released during melting, the outermost layer itself becomes a clean film free of impurities, improving solder wettability and soldering reliability. This will lead to an improvement in The electrode treatment simply involves moving the semiconductor device from the high-temperature part to the low-temperature part in the high-boiling liquid, and can be easily carried out without using complicated equipment. Also. Melting and cooling are performed in such a high boiling point liquid, and since the electrodes of semiconductor devices do not stick together in the low-temperature part, it is possible to input large quantities of semiconductor devices in a separate state without aligning them during electrode processing. Moreover, since the semiconductor device is in contact with the liquid, heating and cooling can be completed in a short time, making it extremely suitable for mass production. Furthermore, since the material is melted and cooled in a high boiling point liquid and has no chance of coming into contact with air, there is no fear that the surface of the electrode portion will be oxidized even during melting. Furthermore, performing melting processing in a liquid means that the specific gravity of the high-boiling liquid that is in contact with the molten material (low-melting point metal or low-melting point alloy) is high compared to air, and the viscosity is also high. Therefore, pressure is applied to the molten metal from the surroundings, and the molten metal surface becomes smooth without undulations and has a uniform thickness. Note that by using a liquid with a fluxing effect such as oil such as natural vegetable oil or glycerin as a high boiling point liquid, flux becomes unnecessary, which simplifies the equipment and reduces the processing cost of processed semiconductor devices. Cleaning is also very easy. Further, as the low melting point metal film (low melting point alloy film), a film composed of an electroplated film or a chemically plated film is advantageous in making the thickness uniform.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method for processing electrodes of a semiconductor device according to the present invention.

In FIG. 1, reference numeral 5 denotes a semiconductor device having the structure shown in FIGS. 3 and 4, and is denoted by the same reference numeral as in FIG. 15 is about 160 in length, for example.
cm, is a glass cylindrical container with an inner diameter of approximately 9 cm, and here it is installed vertically. 16 is coconut oil, which is a natural vegetable oil, placed in this container 15;
7 is a heater such as a mantle heater provided on the upper outer periphery of the cylindrical container 15, and 18 is a parts feeder for feeding the semiconductor device 5 into the container 15 from the upper opening of the cylindrical container 15. .

This embodiment is an example in which the cylindrical container 15 is installed vertically as described above, and is a basic apparatus configuration for carrying out the method of the present invention.

Next, a method for processing the surface of the electrode portion of the semiconductor device 5 using the apparatus shown in FIG. 1 will be described. First, a glass cylindrical container 15 is heated using a heater 17.
Heat the top of the container to 250-280℃. At this time, since the coconut oil 16 is contained inside the cylindrical container 15, the coconut oil 16 is heated to 250 to 280°C. The heated coconut oil 16 has a low specific gravity and causes convection only in the upper part without convection to the low temperature part where the specific gravity is higher in the lower part. Therefore, a temperature gradient is created in the coconut oil 16 in the cylindrical container 15 from a high temperature state to a low temperature state from the upper part to the lower part, and the lower part side can maintain normal temperature. Once the above preparations have been completed, the semiconductor device 5 is introduced from the parts feeder 18 into the cylindrical container 15 from above the surface of the coconut oil 16. Here, the semiconductor device 5 used in this example
is a PLCC type semiconductor device, and the structure of the electrode part is Cu, the base plating is Ni, and the outermost layer (low melting point metal plating film) is an electroplated film with a thickness of 7 to 10 μm with Sn:Pb = 60:40. It is something that we have. Further, the melting point of the outermost layer material is 180 to 190°C.

Then, using the parts feeder 18, the semiconductor devices 5 having the above specifications are dropped into the heated palm oil 16 at a speed equivalent to 180 devices. As a result, the semiconductor device 5 hits the surface of the coconut oil 16 and falls through the coconut oil 16. At this time, the coconut oil 16 and the semiconductor device 5
Due to the friction of As the coconut oil 16 falls into the low-temperature part attached to it, the molten part solidifies from the moment it passes the part where the temperature of the coconut oil 16 drops to approximately 180°C or less.
The semiconductor device 5 having a smooth surface electrode is collected at the bottom of the cylindrical container 15. At this time, since the bottom of the cylindrical container 15 is at room temperature, there is no fear that the electrodes will stick together even if the semiconductor devices 5 come into contact with each other. Here, regarding the method for taking out the semiconductor device 5 after the electrode surface treatment, for example, take out the high temperature part of the coconut oil 16 and take it out from the parts input port, or put a stopper on the bottom of the cylindrical container 15. A possible method is to remove the coconut oil along with the coconut oil 16 by opening the stopper. In this way, the semiconductor device 5
The low melting point metal plating film is melted.

Next, other embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a schematic configuration diagram showing another example of an apparatus for carrying out the method for processing electrodes of a semiconductor device according to the present invention.

In FIG. 2, reference numeral 5 denotes a semiconductor device having the structure shown in FIG. 4, and is denoted by the same reference numeral as in FIG. Since the semiconductor device 5 in FIG. 2 is of the DIP type, the external lead-out electrode 3 is shaped like a centipede's foot as shown in FIG. Therefore, if the DIP type semiconductor device 5 is introduced from above the cylindrical container 15 installed vertically as in the embodiment shown in FIG. .

Therefore, in this device, as shown in FIG. 2, the cylindrical container 15a is tilted, and the DIP type semiconductor device is transported from the parts feeder 18 with the external lead-out electrode 3 shown in FIG. 4 facing upward. 5 into the cylindrical container 15a. While sliding down the slope of the cylindrical container 15a, the loaded semiconductor device 5 moved from the high temperature side of the coconut oil 16 to the low temperature side, and was placed in communication with the bottom side of the cylindrical container 15a. It accumulates in the storage tank 19. Coconut oil 1 in this storage tank 19
Since the semiconductor devices 6 are not affected by heating by the heater 17 and are kept at room temperature, the accumulated semiconductor devices 5 can be taken out from the upper opening side of the storage tank 19. At this time, a mesh receptacle is placed in advance on the inner bottom surface of the storage tank 19, and when the processed semiconductor devices 5 are accumulated therein, feeding from the parts feeder 18 is stopped, the mesh receptacle is pulled up, and the processed semiconductor devices 5 are collected in the storage tank 19. It is preferable to take out the semiconductor device 5.

In this embodiment, the semiconductor device 5 is a DIP type semiconductor device, and the structure of the external lead-out electrode 3 is made of Cu as a material and a low melting point metal plating film on top of it.
It has an electroplated film with a thickness of 7 to 10 μm with Sn:Pb=60:40. Then, using the parts feeder 18, the semiconductor devices 5 having the above specifications are dropped onto the surface of the heated coconut oil 16 at a rate of 120 pieces/minute. As a result, the semiconductor device 5 slides down the inner wall surface of the inclined cylindrical container 15a, for example, and the storage tank 1
It got to 9. When the accumulated semiconductor device 5 was taken out, the surface of the Sn--Pb alloy plating film was smooth as in the embodiment shown in FIG. 1 above. Here, the state of melting and solidification of the Sn--Pb alloy plating film in the coconut oil 16 is the same as in the embodiment shown in FIG. 1, and detailed explanation will be omitted.

In the above embodiments, the present invention has been explained using PLCC type and DIP type semiconductor devices as examples, but the present invention is not limited thereto. It goes without saying that it can be applied to all semiconductor devices equipped with melting point alloy films, but also to quad flat package (QFP), small outline package (SOP), small outline bent package (SOJ) type semiconductor devices, etc. .

Furthermore, in the above example, a case was explained in which coconut oil, which is a natural vegetable oil, was used as the high boiling point liquid; Alternatively, materials with a flux action such as glycerin can be used to have the same effect, and in addition to these materials, the melting point of the molten material (low melting point metal film) in the electrode part of the semiconductor device can be used. Any high boiling point liquid can be used as long as it has a high boiling point. Furthermore, the outermost layer of the electrode part of the semiconductor device to be melted is not limited to a low melting point metal plating film (low melting point alloy plating film) composed of electroplating or chemical plating, but may be formed by thermal spraying, vapor deposition, etc. There is no problem even if it is a low melting point metal film (low melting point alloy film). Furthermore, as the material constituting these low melting point metal films (low melting point alloy films), in addition to the solder of the above embodiments, commonly used tin, lead, and the like can be used.

The low melting point metal film (low melting point alloy film) preferably has a melting point of 100 to 550°C and a film thickness of 1 μm or more. First, if the melting point is less than 100℃, the re-melted metal film may melt due to self-heating during use of the component after soldering, and if it exceeds 550℃, the internal semiconductor and coating material may be destroyed. Therefore, there is a possibility that the performance as a semiconductor device cannot be maintained. Furthermore, if the film thickness is less than 1 μm, a uniform film cannot be formed after heat treatment, which reduces the reliability of soldering during mounting and may lead to oxidation during storage. This film thickness is 8~
Experiments have confirmed that 15 μm is extremely easy to solder.

Effects of the Invention As described above, the method for processing electrodes of a semiconductor device according to the present invention is configured and has many features. First, the low melting point metal film (low melting point alloy film) is melted on the high temperature side of the high boiling point liquid in the container and cooled on the low temperature side, so surface tension acts during melting and the surface area becomes smaller.
By being cooled in this state, the surface area becomes extremely small compared to a low melting point metal film (low melting point alloy film) formed with plating film, etc., and the surface becomes smooth, so that it can be stored easily. Adhesion of foreign matter and adsorption of gas are extremely reduced. Additionally, since foreign substances and gases adsorbed or occluded on the surface or inside the recesses are released during melting, the outermost layer itself becomes a clean film free of impurities, improving solder wettability and soldering reliability. will be improved. The electrode treatment simply involves moving the semiconductor device from the high-temperature part to the low-temperature part in the high-boiling liquid, and can be easily carried out without using complicated equipment. In addition, since the semiconductor devices are melted and cooled in the high-boiling point liquid and the electrodes of the semiconductor devices do not stick together in the low-temperature side, the semiconductor devices do not have to be aligned during electrode processing and are disassembled in large quantities. Processing can be done simply by putting the semiconductor device into the liquid, and since the semiconductor device is in contact with the liquid, heating and cooling can be completed in a short time, making it extremely suitable for mass production. Furthermore, since the material is melted and cooled in a high boiling point liquid and has no chance of coming into contact with air, there is no fear that the surface of the electrode portion will be oxidized even during melting. Furthermore, performing melting processing in a liquid means that the specific gravity of the high-boiling liquid that is in contact with the molten material (low-melting point metal or low-melting point alloy) is high compared to air, and the viscosity is also high. Therefore, pressure is applied to the molten metal from the surroundings, and the molten metal surface becomes smooth without undulations and has a uniform thickness. Note that by using a liquid with a fluxing effect such as oil such as natural vegetable oil or glycerin as a high boiling point liquid, flux becomes unnecessary, which simplifies the equipment and reduces the processing cost of processed semiconductor devices. Cleaning is also very easy. Further, as the low melting point metal film (low melting point alloy film), a film composed of an electroplated film or a chemically plated film is advantageous in making the thickness uniform.

Furthermore, the effects of the present invention are listed below.

Since the semiconductor devices can be loaded without lining up, the semiconductor devices can be processed with the same equipment regardless of their size. Further, it is also possible to process a mixture of semiconductor devices having different sizes.

Since the process can be performed without using flux, cleaning is easy, and the finished product is clean with no flux sticking.

Since the heat medium is a high-boiling point liquid, temperature control is highly accurate.Since the high-boiling point liquid and the semiconductor device are in contact, heat transfer is fast, and melting and solidification processes can be performed in a short time, and the melting process is reliable. Highly sexual. In other words, there is no melting failure.

Since the high-boiling point liquid has a temperature gradient, processed semiconductor devices can be stored in a pile in the low-temperature section at once, and can be taken out all at once, greatly simplifying the removal work.

By selecting the type or specific gravity of the high boiling point liquid, the passage time of the semiconductor device through the liquid can be changed. Furthermore, by changing the temperature gradient of the high-boiling point liquid, the specific gravity changes, so the passage time of the semiconductor device through the liquid can be changed as well. Thereby, even if the type or size and shape of the low melting point metal film or low melting point alloy film of the semiconductor device changes, it can be easily handled.

Since there are no mechanically moving parts, there are no equipment failures and the operating rate is dramatically improved.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an apparatus for carrying out the method for processing electrodes of chip parts according to the present invention, and FIG. 2 is a schematic diagram showing an example of another apparatus for carrying out the method of the present invention. Configuration diagram, Figure 3a,
4b and 4 are each a type of semiconductor device. A perspective view showing a PLCC type and DIP type semiconductor device,
A cross-sectional view, a perspective view, and FIG. 5 are schematic configuration diagrams showing an example of an apparatus for carrying out a conventionally known method for processing electrodes of a semiconductor device. 1... Si pellet, 2... Bonding wire, 3... External lead-out electrode, 4... Resin, 5...
Semiconductor device, 15, 15a... Cylindrical container, 16...
...Coconut oil (high boiling point liquid), 17... Heater, 18
...Parts feeder, 19...Storage tank.

Claims (1)

[Claims] 1. A semiconductor device in which a high boiling point liquid such as oil is placed in a cylindrical container, a temperature gradient is created in the high boiling point liquid in the container, and a low melting point metal film or a low melting point alloy film is held on the electrode. is moved from the high-temperature part of the high-boiling liquid in the container to the low-temperature part, and the low-melting metal film or low-melting alloy film of the electrode part is melted in the high-temperature part, and then cooled in the low-temperature part. , an electrode processing method for a semiconductor device in which a molten portion is solidified. 2. Electrode treatment of a semiconductor device according to claim 1, using any one of natural vegetable oil, natural animal oil, natural mineral oil, synthetic silicone oil, or glycerin as the high boiling point liquid. Method. 3. The electrode processing method for a semiconductor device according to claim 1, wherein the low melting point metal film is made of tin or lead. 4. A method for processing electrodes of a semiconductor device according to claim 1, which uses solder for the low melting point alloy film. 5. The electrode processing method for a semiconductor device according to claim 1, wherein the low melting point metal film or the low melting point alloy film is an electroplated film or a chemically plated film.