JPH0545043B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an electrode processing device for chip components such as chip resistors, which are a type of electronic component that contributes to the reduction in weight, thickness, and size of electronic devices. be.

BACKGROUND ART Conventionally, this type of chip component has had a structure as shown in FIG. Figure 2 shows a cross-sectional view of a square plate type chip resistor as an example, in which 1 is an insulating substrate such as alumina, 2 is a resistor, 3 is a silver-based electrode film, and 4
5 is a nickel (Ni) film, 5 is a solder (Sn-Pb alloy) [or tin (Sn) or lead (Pb)] film deposited by electroplating, and 6 is the above resistor 2.
It is a glass coating membrane to protect the

In this way, conventional chip parts have a low melting point gold 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 a base layer (hereinafter referred to as a low melting point metal plating film). In this case, the nickel film 5) is a high melting point metal film or a high melting point alloy film (hereinafter referred to as a high melting point metal film) made of a material that has a higher melting point than the above-mentioned low melting point metal plating film and has good affinity with the low melting point metal plating film. (collectively referred to as ) is formed.

In chip components with such a conventional configuration, the outermost layer of the electrode part 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, an atmospheric furnace, an infrared furnace, a hot air furnace, a hot plate, etc. are used as an electrode processing device to smoothen the low melting point metal plating film, which has a rough surface as described above. Known devices include heated electrode processing devices and devices that utilize the vapor phase soldering method (VPS method).
Among them, as an example, an electrode processing apparatus for chip parts using an infrared heater will be described below.

FIG. 3 shows a schematic diagram of an electrode processing apparatus using this infrared heater.

In FIG. 3, 7 is a chip component having the structure shown in FIG. 2, 8 is a chip component alignment machine,
9 is a flux coating machine, 10 is an infrared heater, 1
Reference numeral 1 designates a cooler, 12 a machine for removing electrode-treated chip parts, 13 a belt drive section, 14 a stand for the electrode processing apparatus, 15 a chip part conveyor belt, and 16 a belt washer.

The process of melting the low melting point metal plating film on the electrode part of the chip parts is as follows: (1) Aligning the chip parts → (2) Applying flux → (3) Melting by heating → (4) Cooling and solidifying → (5) Chip parts It consists of 5 steps for extraction.
That is, the chip part aligning machine 8 is placed on the chip part conveying belt 15 conveyed by the belt drive unit 13.
After supplying the chip part 7 from the chip part 7 and applying flux to the chip part 7 in the next step, the electrode part to which the flux has been applied is heated and melted by a tunnel-type infrared heater 10, and then the molten part is passed to the cooler 11. After that, the electrode-treated chip component 7 is taken out by the electrode-treated chip component removal machine 12. Moreover, after the chip parts conveying belt 15 is cleaned by the belt washer 16,
Chip parts 7 are being supplied again.

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

Problems with the above-described electrode treatment device will be listed below.

(1) When the electrode parts of the chip parts are melted, the individual chip parts must be aligned at intervals so that the electrode parts of the chip parts do not touch each other, and this is a major problem that hinders mass production. It becomes a factor.

(2) Because the metal is heated and melted in air, flux is required to prevent oxidation of the molten metal surface.

(3) Since flux is used, the flux gets heated and burns into the chip parts, making it difficult to clean the chip parts.

(4) Since the heating section is a tunnel type, air can freely enter and exit, making it difficult to stabilize the temperature.

(5) 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 a cooler for rapid cooling.

(6) Flux adheres to the conveyor belt and may cause equipment failure, so the conveyor belt must be cleaned.

(7) Considering the equipment as a whole, 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 apparatus using the infrared heater shown in FIG. 3 has many problems, and there is a strong demand for improvement thereof.

Further, the other electrode processing apparatuses mentioned above also have problems similar to the electrode processing apparatus using this infrared heater, to a greater or lesser extent. And the dimensions of chip parts are generally 3.2
Small as mm×1.6mm, and even more recently 2.0mm×
Very small chip parts such as 1.25mm are being used, and there is a growing trend towards miniaturization. In this way, the dimensions of the chip parts are extremely small, and as mentioned above, the conventionally known electrode processing equipment has many problems, so the current chip The reality is that almost no treatment is performed to make the surfaces of electrode parts smooth in parts.

The present invention solves the above-mentioned problems with the electrode parts of chip parts, reduces the surface area of the electrode part of chip parts, and smooths it to improve solder wettability and provide reliable soldering for long-term storage. The first object of the present invention is to provide an electrode processing device that can improve performance. A second object of the present invention is to solve the problems of conventionally known electrode processing devices, eliminate mechanically moving parts, and allow chip parts to be inserted without being aligned.
To enable melting processing without the electrode parts of chip parts touching each other during melting, to control the melting temperature with precision, and to process electrodes of chip parts with good mass productivity without using flux. The purpose is to

Means for Solving the Problems In order to solve the above problems, the present invention has a high melting point metal film or a high melting point alloy film as a base layer on both ends of an insulating substrate, and a low melting point film as an outermost layer. An electrode processing device for chip parts having an electrode part with a metal film or a low melting point alloy film includes a cylindrical container filled with a high boiling point liquid such as oil and equipped with a charging part at one end into which chip parts are put. , a heater arranged at one end of the cylindrical container so as to create a temperature gradient in the high boiling point liquid, and two or more heaters arranged at intervals at the other end of the cylindrical container. The above-mentioned pot is installed below the cylindrical container, and is provided with a take-out part for taking out the processed chip parts on the side of the pot. The lower pot is closed and the upper pot is left open. When removing the processed chip parts, the upper pot is closed and then the lower pot is opened. In a preferred embodiment, the high boiling point liquid is one of natural vegetable oil, natural animal oil, natural mineral oil, synthetic silicone oil, or glycerin.

Effect According to this configuration, low melting point metal (low melting point alloy)
A film or layer consisting of a high-boiling liquid is melted on the high-temperature side of the container and cooled on the low-temperature side, so surface tension acts during melting, reducing the surface area, and the liquid is cooled in this state. According to
Compared to low melting point metal films (low melting point alloy films) formed with plating films, the surface area is extremely small, and the surface is also smooth, so there is extremely little adhesion of foreign matter or gas adsorption during storage. This means that chip parts can be obtained. 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 results in chip parts that lead to improved performance. The electrode treatment simply involves moving the chip parts from the high-temperature side to the low-temperature side in the high-boiling liquid, and can be easily carried out without using complicated equipment. In addition, since melting and cooling are performed in a high-boiling liquid, and the electrodes of the chip parts do not stick together in the low-temperature part, the chip parts do not have to be aligned during electrode processing, and a large amount of chip parts can be disassembled and disassembled. Processing can be done simply by putting the chip into the liquid, and since the chip parts are in contact with the liquid, heating and cooling can be completed in a short time, making it highly 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 point liquid that is in contact with the molten material (low melting point metal, low melting point alloy, etc.) is high compared to air, and the viscosity is also high. Because of this, pressure is applied to the molten metal from the surroundings, and the molten metal surface becomes smooth without undulations and has a uniform thickness. In addition, 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 need for processed chip parts. Cleaning is also very easy.
In addition, since the pots are arranged in series below the cylindrical container, when removing electrode-treated chip parts, the liquid level of the high boiling point liquid can be removed without changing.
Moreover, it is possible to take out the high boiling point liquid without mixing air into it.

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 electrode processing apparatus for chip parts according to the present invention.

In FIG. 1, numeral 7 designates a chip component having the structure shown in FIG. 2, and is designated by the same reference numeral as in FIG. Reference numeral 17 is a glass cylindrical container, for example, about 160 cm long and about 9 cm in inner diameter from the top end to the bottom end, and is installed vertically here. 18 is coconut oil, which is a natural vegetable oil, placed in this container 17; 19 is the cylindrical container 17;
A heater such as a mantle heater 20 provided on the upper outer periphery of the cylindrical container 17 is a parts feeder for feeding the chip parts 7 into the cylindrical container 17 through an opening on the upper surface thereof.

Reference numerals 21 and 22 are handles provided in series at an appropriate interval in the narrow portion of the lower end of the cylindrical container 17. used. Reference numeral 23 denotes a high boiling point liquid storage container for taking out the processed chip parts 7 without changing the liquid level of coconut oil 18, which is a high boiling point liquid used in this electrode processing device. The bottom opening 24 at the tip is placed in the coconut oil 18 filled in the reservoir 23. Reference numeral 25 denotes a net-shaped receiver for taking out the processed chip parts 7 from the coconut oil 18 in the high-boiling liquid reservoir 23 without moving the high-boiling liquid reservoir 23.

This embodiment is an example in which the cylindrical container 17 is installed vertically as described above, and is the basic configuration of the apparatus of the present invention.

Next, a method for treating the surface of the electrode portion of the chip component 7 using the apparatus shown in FIG. 1 will be described. First, in the stage of performing electrode processing, the upper pot 21 is opened and the lower pot 22 is closed, as shown in FIG. Even in this state, the heater 19 is used to heat the upper part of the glass cylindrical container 17 to
Heat to 280℃. At this time, since coconut oil 18 is contained inside the cylindrical container 17, the coconut oil 18
Heated to 250-280℃. The heated coconut oil 18 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 high in the lower part. Therefore, a temperature gradient is created in the coconut oil 18 in the cylindrical container 17 from the upper part to the lower part, from a high temperature state to a low temperature state, and the bottom side can maintain room temperature. Once the above preparations have been completed, the chip parts 7 are introduced from the parts feeder 20 into the cylindrical container 17 through the input section above the surface of the coconut oil 18. Here, the chip parts 7 used in this example
is a square plate type chip resistor, and the structure of the electrode part is Ag-Pd for the bottom layer, Ni for the middle layer, and the outermost layer (low-melting metal plating film) has a thickness of 7 to 10 μm with Sn:Pb=60:40.
It has an electroplated film. Further, the melting point of the outermost layer material is 180 to 190°C.

Then, using the parts feeder 20, the chip parts 7 having the above specifications are dropped into the heated coconut oil 18 at a rate of 250 pieces/minute. As a result, the chip part 7 hits the surface of the coconut oil 18 and falls through the coconut oil 18. At this time, due to the friction between the coconut oil 18 and the chip part 7, the chip parts 7 fall individually and are heated to a high temperature of 250 to 280°C. - The Pb alloy plating film is melted and falls into a low temperature area with a temperature gradient, and when it passes through the area where the temperature of the coconut oil 18 is approximately 180℃ or less, the molten area solidifies and the surface A tip 22 on the bottom side in the cylindrical container 17 serves as a chip part 7 having a smooth electrode.
It accumulates on top. At this time, since the bottom of the cylindrical container 17 is at room temperature, there is no fear that the electrodes will stick together even if the chip parts 7 come into contact with each other. In order to take out the chip part 7 that has undergone electrode surface treatment, as described above, during the electrode treatment, the pot 21 is opened and the pot 22 is closed. Now, when the processing is completed, the pot 21 is closed and the pot 22 is opened with the bottom opening 24 of the cylindrical container 17 held below the liquid level by the high boiling point liquid storage container 23. falls onto the net-like receiver 25 due to its own weight.
Next, after confirming that the oil has finished falling, the mesh receptacle 25 is pulled up from the palm oil 18 in the storage container 23, thereby completing the extraction.

When electrode processing is to be continued, the pot 22 is closed, the pot 21 is opened, and the chip parts 7 are fed from the parts feeder 20. By repeating this process, continuous work becomes possible. In this manner, the low melting point metal plating film of the chip component 7 is melted. Furthermore, the chip component 7 that has been taken out can be made into a finished product by simply washing it.

According to this electrode processing device, the coconut oil 18 does not flow out to the bottom, and air does not enter through the bottom opening 24, so the liquid level in the cylindrical container 17 does not change.

Here, 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, but this also includes natural animal oil, natural mineral oil, synthetic silicon oil, Materials with a flux action such as oil or glycerin can be used to have the same effect, and in addition to these materials, they can also be used for melting (low-melting point metal films) in the electrodes of chip parts. Any high-boiling liquid having a boiling point higher than the melting point can be used. In addition, an example was described in which a mantle heater or the like was installed as a heater on the upper outer periphery of the cylindrical container, but in this case, a closed-type sheathed heater was installed inside the upper part of the cylindrical container to heat a high boiling point liquid from inside. It is okay to do so. Furthermore, 2
Although the case where three or more kettles are provided has been described, there is no particular problem even if three or more kotts are provided. For example, in the case of three chips, it is possible to perform electrode processing continuously without interrupting the electrode processing by opening and closing the cap according to changes in the type of chip parts, etc.

The outermost layer of the electrode part of the chip component to be melted in the apparatus of the present invention is not limited to a low melting point metal plating film (low melting point alloy plating film) composed of electroplating or chemical plating, but can also be formed by thermal spraying or vapor deposition. There is no problem even if it is a low melting point metal film (low melting point alloy film) formed by, etc. Also,
In addition to the solder of the above-mentioned embodiments, commonly used materials such as tin and even lead can be used as materials constituting these low-melting point metal films (low-melting point alloy films).

The melting point of the low melting point metal film (low melting point alloy film) is preferably 100 to 550°C, and the film thickness is preferably 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 resistor and coating may be destroyed. There is a risk that the performance as a chip component may not 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 to 15μ
It has been confirmed through experiments that soldering is extremely easy with m.

Further, the electrode processing device according to the present invention has a solderable metal film or alloy film made of copper or copper alloy, and has a layer in which a low melting point metal paste or a low melting point alloy paste is applied and dried as the outermost layer. It can also be applied to chip parts.
In this case, it goes without saying that the melting point of the solderable metal film (alloy film) as the base layer is higher than the melting point of the high boiling point liquid. When a chip component having the outermost layer coated with this low melting point metal (low melting point alloy) paste and dried is subjected to electrode treatment using the device of the present invention, the layer made of the low melting point metal (low melting point alloy) paste is electrically This is more advantageous than a plating film or a chemical plating film in terms of making the thickness, which is related to soldering reliability, thicker and more uniform. In addition, low melting point metal (low melting point alloy) paste usually contains flux, but this flux dissolves in high boiling point liquid when melted, so it does not seize or impair its effectiveness. It is. In a chip component having this structure, the thickness of the layer made of the low melting point metal (low melting point alloy) paste is preferably 3 .mu.m or more in a dry state, and a thickness of 25 to 100 .mu.m is particularly suitable.

Effects of the Invention As described above, the electrode processing device for chip parts according to the present invention is constructed and has many features. First, a film or layer made of a low melting point metal (low melting point alloy) 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 that of a low melting point metal film (low melting point alloy film) formed by plating, etc., and the surface becomes smooth during storage. This makes it possible to obtain chip parts with extremely low adhesion of foreign matter and gas adsorption. 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 results in chip parts with improved performance. The electrode treatment simply involves moving the chip parts from the high-temperature side to the low-temperature side in the high-boiling liquid, and can be easily carried out without using complicated equipment. In addition, since melting and cooling are performed in a high-boiling liquid, and the electrodes of the chip parts do not stick together in the low-temperature part, the chip parts do not have to be aligned during electrode processing, and a large amount of chip parts can be disassembled and disassembled. Processing can be done simply by putting the chip into the liquid, and since the chip parts are in contact with the liquid, heating and cooling can be completed in a short time, making it highly suitable for mass production. Furthermore, melting in high boiling point liquid,
Since cooling is performed and there is no opportunity for contact with air, there is no fear that the surface of the electrode portion will be oxidized even when melted. Furthermore, performing melting processing in a liquid means that the specific gravity of the high boiling point liquid that is in contact with the molten material (low melting point metal, low melting point alloy, etc.) is high compared to air, and the viscosity is also high. Because of this, pressure is applied to the molten metal from the surroundings, and the molten metal surface becomes smooth without undulations and has a uniform thickness. In addition, 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 need for processed chip parts. Cleaning is also very easy.

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

(1) Since chip parts can be input without arranging them, they can be processed with the same equipment regardless of their size. It is also possible to mix and process chip parts of different sizes.

(2) Since the process can be performed without using flux, cleaning of chip parts is easy, and the finished product is clean with no flux sticking.

(3) Since the heating medium is a high-boiling point liquid, temperature control is highly accurate, and since the high-boiling point liquid and chip parts are in contact, heat conduction is fast, and melting and solidification processes can be performed in a short time. High processing reliability. In other words, there is no melting failure.

(4) Since the high-boiling point liquid has a temperature gradient, processed chip parts 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. .

(5) By selecting the type or specific gravity of the high boiling point liquid, the passage time of the chip parts in the liquid can be changed. In addition, by changing the temperature gradient of the high-boiling liquid, the specific gravity changes, so that the transit time of the chip part through the liquid can also be changed. Thereby, even if the type or size and shape of the film or layer made of the low melting point metal or low melting point alloy of the chip component changes, it can be easily handled.

(6) Since there are no mechanically moving parts, it can be said that there are no equipment failures, and the operating rate is dramatically improved.

(7) Since the pots are arranged in series at the bottom (bottom) of the cylindrical container, when removing chip parts that have been processed with electrodes, the liquid level of the high-boiling point liquid does not change, and the high-boiling point liquid It can be taken out without mixing air inside.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an embodiment of the electrode processing device for chip parts according to the present invention, Fig. 2 is a sectional view showing a square plate chip resistor which is a type of chip part, and Fig. 3 is a conventionally known 1 is a schematic configuration diagram showing an example of an apparatus for performing electrode processing on a chip component. DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2... Resistor, 3... Silver-based electrode film, 4... Nickel film, 5... Solder film, 6...
...Glass coating film, 7... Chip parts, 17... Cylindrical container, 18... Coconut oil (high boiling point liquid), 19...
... Heater, 20 ... Parts feeder, 21, 22
... Kotoku, 23 ... High boiling point liquid storage container, 24
...Bottom opening, 25...mesh receptacle.

Claims (1)

[Scope of Claims] 1. A chip component having an electrode portion having a high melting point metal film or a high melting point alloy film as a base layer and a low melting point metal film or a low melting point alloy film as the outermost layer at both ends of an insulating substrate. In an electrode processing device, the cylindrical container is filled with a high boiling point liquid such as oil and has an input section at one end into which chip parts are input, and the cylindrical container is configured to have a temperature gradient in the high boiling point liquid. a heater disposed at one end of the cylindrical container, and two or more pots arranged at intervals at the other end of the cylindrical container, and the pots are arranged below the cylindrical container. At the same time, the chip part is equipped with a take-out part for taking out the processed chip parts, and when the chip parts are loaded and processed, the lower part of the part is closed, and the upper part is left open. An electrode processing device for chip parts, characterized in that when taking out the processed chip parts, the upper part is closed and then the lower part is opened. 2. Electrode treatment of chip parts 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. Device. 3. The electrode processing device for chip parts according to claim 1, which uses a maltor heater that heats from the outside or a closed-type sheathed heater that heats from the inside as the heater.