JPH09137297A - Drying method for article to be plated and drying device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dehydrating and drying device which lower the sticking defect rate of articles to be plated by taking advantage of the effectiveness of a barrel solder plating method by a weakly acidic solder plating liquid. SOLUTION: The articles to be plated are subjected to barrel plating in a weakly acidic solder plating bath and, thereafter, hot air of <=70 deg.C is blown to the articles to be plated to dehydrate and dry the articles to be plated. The hot air pressure dehydrating and drying device 1 for the articles to be plated has a drying chamber 9 which houses the articles to be plated subjected to the barrel plating in the weakly acidic solder plating bath, a hot air passage 6 which blows the hot air into the drying chamber 9, a fan 3, a heater section 5 which warms the air, a cooling pipe 12 which cools and dehumidifies the high-humidity air past the drying chamber 9 and a wind path 4 which feeds the dehumidified air to the heater section 5 side by the fan 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for drying a barrel-plated object to be plated.

[0002]

2. Description of the Related Art Barrel plating is known as a solder plating method for applying solder plating to the terminal electrodes of electronic parts such as chip resistors. In this barrel plating method, an object to be plated such as electronic parts is stored in a porous barrel made of an electrical insulator such as plastic, a cathode tangular is inserted, and this barrel is immersed in a plating tank and vibrated and rotated. Plating. At this time, an appropriate amount of a dummy made of iron balls is mixed into the object to be plated in order to make the current flow between the objects to be plated uniform.

As the solder plating solution used in the barrel plating method, a strongly acidic solder plating solution having a pH of 1 or less containing divalent tin ions, divalent lead ions, free acid, and a brightener is used, and an object to be plated is used. After pretreatment such as degreasing and pickling, barrel plating was performed through each step of nickel plating and strongly acidic solder plating, and dehydration and drying were performed by a centrifugal dehydration drying device.

In the dehydration drying method using the centrifugal dehydration drying apparatus, the dehydration basket containing the object to be plated by the barrel plating method and the dummy is set in the basket of the centrifugal dehydration drying apparatus and rotated, and the liquid is cut by the centrifugal force. At the same time as the dehydration, hot air (temperature of 100 to 150 ° C.) is blown onto the dehydration basket to perform drying (drying time of about 20 minutes).

By the way, when the above strongly acidic solder plating solution is used in the barrel plating method, a large number of objects to be plated are stuck to each other due to the metal deposition structure during plating.

Further, the objects to be plated that have been dehydrated and dried by the centrifugal dewatering / drying device make the sticking between the objects to be plated generated in the plating process stronger by centrifugal force, temperature and time. There was no choice but to perform a sorting process for sticking products in the process, and there was a loss of providing a sorting work process.

[0007]

In view of the above problems, the present invention reduces the occurrence of sticking defects and utilizes the effectiveness of the barrel solder plating method with a weakly acidic solder plating solution, and a method for drying an object to be plated. It proposes a dryer.

[0008]

The method of drying an object to be plated according to the present invention is characterized in that the object to be plated is barrel-plated in a weakly acidic solder plating bath, and then hot air is blown into the object to be dried. And The apparatus for drying an object to be plated of the present invention includes a drying chamber for accommodating an object to be plated that has been barrel-plated with a weakly acidic solder plating bath, a hot air passage for blowing hot air into the drying chamber, a fan, and warming air. A heater, a dehumidifying unit that cools and dehumidifies the high-humidity air that has passed through the drying chamber, and an air passage that sends air dehumidified by the dehumidifying unit to the heater unit side by the fan. Characterize.

[0009]

EXAMPLES In the present invention, first, in order to reduce the number of sticking defects, a weakly acidic (PH 3 to 5) solder plating solution is used as the solder plating solution used for barrel plating.
An object to be plated, for example, a plating film in a metal deposition state in which sticking of chip resistors is unlikely to occur is obtained. As a general solder plating liquid of the weakly acidic barrel plating liquid,
A plating solution composed of a divalent tin compound, a divalent lead compound, a chelating agent, and a conductive salt is used.

As a result of subjecting the object to be plated to barrel plating using the weakly acidic solder plating solution, it was possible to reduce the sticking at the stage of plating.

By the way, even if it is possible to reduce sticking at the stage of the plating process by using the weakly acidic solder plating solution, if the centrifugal dehydration drying apparatus is used for dehydration drying as in the conventional case,
The adhesion between the objects to be plated generated in the solder plating process is made stronger by centrifugal force, temperature and time. Therefore, in the present invention, the following drying method and drying apparatus are adopted to stop the progress of the degree of sticking of the adhered objects to be plated and prevent the solder plating from deteriorating.

FIG. 1 shows an embodiment of a hot air pressure dewatering / drying apparatus 1 of the present invention. In FIG. 1, reference numeral 2 denotes a housing, and a fan 3 such as a ring blower is provided in the housing 2, and air warmed by the fan 3 is circulated for drying.

The air sent from the fan 3 passes through the ventilation passage 4 and is warmed by the heater portion 5 (3 kW). The warmed air passes through the ventilation passage 6 and from the warm air outlet 7.
The object 8 to be plated is blown out to a drying chamber 9 for drying. The temperature inside the drying chamber 9 is 70 ° C. or lower, preferably about 6 ° C.
Adjust so that the temperature is around 7 ° C. The temperature is set below 70 ° C because the plating surface changes if the temperature is higher than
This is because the degree of sticking tends to increase.

The entire amount of the air flowing into the drying chamber 9 passes through the gap of the object 8 to be plated contained in the drying basket 11 having the ventilation port 10 at the bottom. At this time, moisture adhering to the object to be plated 8 is pushed out from between the objects to be plated 8 or taken into the air to become high-humidity air, and escapes between the objects to be plated 8 and the drying basket 11.

The high-humidity air that has escaped from the drying basket 11 passes through a cooling chamber 13 provided with a cooling pipe 12 in which cold water at 15 ° C. to 17 ° C. circulates at 10 liters / minute and is dehumidified when passing through this. Separates into dry air and water droplets. Then, the dried air is returned to the heater section 5 side through the fan 3 and the ventilation passage 4 and recirculated, while the water droplets are discharged from the dehydration drain port 14. By repeating this circulation for about 7 minutes, the object 8 to be plated in the dehydration basket 11 is dehydrated and dried.

[0016]

According to the present invention, since the drying temperature is low, the drying time is short, and the centrifugal force is not applied to the objects to be plated as in the conventional case, the progress of the degree of sticking of the objects to be adhered to each other can be prevented and the soldering Prevents deterioration of plating. Since a weak acid solder plating bath is also used in combination with the barrel plating bath, the synergistic effect can significantly reduce the sticking failure rate before the sticking and separation of the objects to be plated. The actual sticking failure rate before sticking separation is
It was possible to significantly reduce the defective rate from the defective rate of 15.0% generated when using the conventional strongly acidic solder plating bath and the centrifugal dehydration drying apparatus to the defective rate of 0.02% according to the present invention.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a warm air pressure dehydration / drying apparatus of the present invention.

[Explanation of symbols]

 3 Fan 5 Heater part 8 Plated object 9 Drying room 12 Cooling tube 13 Cooling room

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Kumano 3-5-3 Asahi-cho, Takamatsu-shi, Kagawa Hayama Industry Co., Ltd.

Claims (4)

[Claims] 1. A method of drying an object to be plated, which comprises barrel-plating the object to be plated with a weakly acidic solder plating bath and then blowing hot air onto the object to be dried. 2. The method for drying an object to be plated according to claim 1, wherein the temperature of the hot air is 70 ° C. or lower. 3. The method for drying an object to be plated according to claim 1, wherein high-humidity air generated by blowing hot air into the object to be plated is cooled to dehumidify, and the dehumidified air is changed to warm air. A method for drying an object to be plated, which comprises blowing air again into the object to be plated and circulating air. 4. A drying chamber for containing an object to be plated that has been barrel-plated with a weakly acidic solder plating bath, a hot air passage for blowing hot air into the drying chamber, a fan, a heater section for warming air, and the drying. Dehumidifying means for cooling and dehumidifying high-humidity air that has passed through the chamber, and an air passage for sending the air dehumidified by the dehumidifying means to the heater section side by the fan, to be plated Warm air pressure dehydration drying equipment.