JPH0722213A - Method for forming solder bump on surface mounting component - Google Patents

Abstract

PURPOSE:To form a thick solder bump on a surface mounting component, e.g. a chip resistor or a semifixed chip resistor employed in an electronic appliance, by feeding power continuously to an outer electrode in a plating liquid without relying on the conventional technology, e.g. presoldering method or barrel plating method, in which the thickness of solder is limited. CONSTITUTION:Chip resistors 1 are set on a carrier tape 5 and carried continuously to a plating bath where power is fed continuously from a power supply electrode 6 to the primary electrode 3a of the chip resistor 1 and the anode 7 is disposed just under the primary electrode 3a thus forming a solder bump 9a selectively. Since a thick solder bump 9a is formed by plating, additional solder supply is not required at the time of mounting on a circuit board, resulting in the enhancement of reliability and efficiency in the mounting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming solder bumps on surface-mounted components such as chip resistors and chip semi-fixed resistors used in various electronic devices.

[0002]

2. Description of the Related Art Conventionally, as a method of forming solder bumps on surface mount components of this type, electrolytic Ni by a pre-solder method using molten solder on an Ag-Pd electrode or a barrel method on a primary electrode made of an Ag-based electrode is used. Also, the solder electrodes are formed by electrolytic solder plating.

[0003]

However, the conventional solder electrodes formed by the preliminary soldering method and the barrel plating method have a uniform solder film having a film thickness of about 3 to 10 μm. Therefore, when mounting on a circuit board or the like, it is necessary to supply solder by cream solder printing.

In recent years, the progress of miniaturization and thinning of electronic devices has been remarkable, and the demand for electronic parts such as minute parts such as 1.0 × 0.5 chip resistors is increasing. There is a problem in the shape management of the solder particles used for cream soldering, fine pattern printing technology, etc. in soldering such minute parts, and it is an exaggeration to say that most of the mounting defects are due to the soldering process. is not.

The present invention is intended to solve the above problems, and it is an object of the present invention to improve the reliability of the mounting work of surface mounting components and to improve the efficiency of the mounting process by eliminating the supply of cream solder or the like. To do.

[0006]

In order to achieve the above-mentioned object, the present invention provides a conveying means for continuously conveying a surface-mounted component having a primary electrode formed on an insulating substrate in advance into a plating tank, and the primary means. In a plating method provided with a power supply electrode that contacts an electrode in a plating solution and continuously supplies power, a solder bump is formed by selectively thickening solder plating on the anode side on the primary electrode. .

[0007]

In the method described above, the solder plating is selectively thickened on the anode side on the primary electrode to form the solder bumps, so that it is not necessary to supply new solder at the time of mounting on the rotating substrate. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the figure, 1 is a chip resistor, 2 is an insulating substrate made of alumina, and 3a and 3b.
Is a primary electrode made of Ag metal glaze, and 4 is the uppermost glass layer. Reference numeral 5 is a carrier tape having holes 3c and 3d in a portion in contact with the primary electrodes 3a and 3b for mounting the chip resistor 1 and continuously carrying it into the plating layer, and 6 is continuously feeding power to the primary electrode 3a. Is a power supply electrode, 7 is a solder plating anode (Sn-Pb), and 8 is a solder plating liquid flow.

In the above structure, when a negative potential is applied to the primary electrode 3a by the power supply electrode 6, a deposition reaction of solder plating occurs on the surface of the primary electrode 3a to form the solder bump 9a. This reaction rate increases as the solder plating liquid flow 8 increases and in inverse proportion to the distance from the anode 7.
In the present invention, by arranging the anode 7 directly below the primary electrode 3a, and by continuously feeding power with the power feeding electrode 6,
The plating deposition rate can be increased, and the solder plating can be selectively thickened on the anode side of the primary electrode 3a.

The primary electrode 3 on the opposite side of the chip resistor 1
The same method is used to form the solder bump 9b on b. Although the chip resistor 1 has been described in the embodiment, the solder plating deposition reaction can be performed on the chip semi-fixed resistor by the same solder bump forming method.

[0011]

As is apparent from the above-described embodiments, the method of forming solder bumps on surface-mounted components according to the present invention is that solder bumps are formed by arranging an anode directly under the primary electrode to selectively thicken the solder plating. This method enables the formation of solder bumps, which was not possible with the conventional method, and improves the reliability and efficiency of mounting by supplying surface mount components with solder bumps. You can measure.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a method for forming solder bumps on surface-mounted components according to an embodiment of the present invention.

FIG. 2 is a sectional view of a chip resistor used in the same solder bump forming method.

FIG. 3 is a sectional view of the same chip resistor with solder plating.

[Explanation of symbols]

 1 Chip Resistor (Surface Mount Component) 2 Insulating Substrate 3a, 3b Primary Electrode 5 Carrier Tape (Conveying Means) 6 Feeding Electrode 7 Anode 9a, 9b Solder Bump

Claims (1)

[Claims] 1. A transfer means for continuously transferring a surface-mounted component having a primary electrode formed in advance on an insulating substrate into a plating tank, and a power supply for continuously supplying power by contacting the primary electrode in a plating solution. In the plating method with electrodes,
A method of forming a solder bump on a surface-mounted component, wherein a solder plating is selectively thickened on the anode side of the primary electrode to form a solder bump.