JPH09199653A - Method of plating very small area - Google Patents

Abstract

PROBLEM TO BE SOLVED: To plate a very small area part uniformly by forming eccentricity between the center of the opening of an area plate and the center of a nozzle hole. SOLUTION: In the plating of the edge part of a lead frame 6 using an area plate 3 and a nozzle plate, the diameter of a nozzle hole 4 is selected to be 1.0mm to 1.2mm and the eccentricity between the center of the opening part 5 of the area plate 3 and the center 8 of the nozzle hole 4 is set to be 0.1 to 0.4mm. With this, problems that are apt to be caused by the insufficient transition of the flow of plating liquid from viscous flow to turbulent flow and spreading of the plating fluid to the surface of a lead frame 6 when the diameter of the opening part 5 is reduced and the problem that the discharging of the plating liquid from the inside of the opening part 5 is difficult are solved, the turbulent flow of the plating liquid on the surface of lead frame 6 that covers the opening part 5 is promoted and the discharging of the plating liquid from the inside of the opening part 5 becomes easier. As the result of it, the plating to a very small area becomes easier and the uniform plating to the very small area of the diameter of 1.5mm becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame plating method, and more particularly to a method of enabling fine plating on a plated portion having a small area.

[0002]

2. Description of the Related Art Lead frames are made of copper or iron alloy material which is punched with a press and surface-treated by electrolytic degreasing, pickling, etc.
For example, the product is obtained by plating copper and silver-plating the lead tips. When the lead tip portion is plated, it is common to plate the portion 0.5 to 1.1 mm from the lead tip portion.

One of such lead frames is a lead-on-chip type or high-density type lead frame. These lead frames have a complicated structure, and the plating areas are set in small, multi-stage, and multi-row, so that the plating efficiency is reduced and the productivity is affected.

Conventionally, such fine area plating uses a nozzle plate 2 provided with a plurality of plating solution jetting nozzles 1 as shown in FIG. 1, and combines an area plate 3 and a nozzle plate 2 as shown in FIG. A lead frame, which is the object to be plated, is installed on the upper surface of the area plate, and the plating solution is ejected from the nozzle holes 4. In addition,
The opening 5 of the area plate is designed in accordance with the lead frame 6 that is the object to be plated. The center 7 of the opening and the center 8 of the nozzle hole are arranged to overlap.

[0005]

By the way, in recent years, it has been required to increase the density of the leads and to make the structure more complicated. For example, not only the lead interval but also the width of the lead itself is required.
It is becoming as narrow as 90 to 200 microns. In order to plate a small area portion having a diameter of about 1.5 mm only on a desired portion of the lead frame tip portion having such a narrow lead width, the lead tip is formed by using the conventional area plate 3 and nozzle plate 2 shown in FIG. There is a problem that if plating is applied to a portion, uneven plating frequently occurs and the yield is significantly reduced.

The present invention was developed in order to overcome such a situation, and an object thereof is to provide a method for uniformly plating a small area having a diameter of about 1.5 mm.

[0007]

The method of the present invention for solving the above-mentioned problems is a method of plating the lead frame tip end portion by using an area plate and a nozzle plate. The center is eccentric.

In the method of the present invention, particularly, when the diameter of the nozzle hole is 1.0 to 1.2 mm, the center of the opening of the area plate and the center of the nozzle hole are eccentric by 0.1 to 0.4 mm. And is effective.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The plating liquid ejected from a nozzle hole rises in the area plate opening, hits the lead frame which is the object to be plated, diffuses on the lead frame surface, and then drops in the area plate opening and is discharged To be done. The plating liquid rising in this opening is laminar,
When it collides with the surface of the lead frame, it becomes turbulent. Then, the plating solution diffuses over the entire surface of the lead frame that covers the opening.

However, as the diameter of the opening becomes smaller, the conversion of the plating solution from a laminar flow to a turbulent flow and the diffusion to the lead frame surface become insufficient, resulting in uneven plating. In addition, it becomes difficult to discharge the plating liquid from the inside of the opening, which also causes uneven plating.

In the method of the present invention, the eccentricity of the center of the opening of the area plate and the center of the nozzle hole promotes turbulence of the plating solution on the surface of the lead frame covering the opening. This is because, in part, a flow is formed in the plating solution in the opening to facilitate discharge of the plating solution from the opening. Hereinafter, the present invention will be described with reference to examples.

[0012]

Next, the present invention will be further described with reference to examples.

(Embodiment 1) A nozzle plate 2 provided with a plurality of plating solution jetting nozzles 1 similar to that shown in FIG. 1 is used, and a lead frame, which is an object to be plated, is set on the upper surface of an area plate 3 as shown in FIG. Then, the plating solution was ejected from the nozzle hole 4 to plate a long piece of 20 pieces / 1 series.

At this time, the diameter of the area opening is 0.3 to
The diameter of the nozzle hole was changed to 2.0 mm, the diameter of the nozzle hole was set to 1.0 mm, and the center of the area opening portion and the center of the nozzle hole were displaced by 0.2 mm, and they were installed as shown in FIG. In addition, the amount of displacement between the center of the area opening portion and the center of the nozzle hole was 0.0 mm, and plating was performed without displacement.

The plating solution used was Ag of 60 to 70 g / liter and pH of 7.8 to 8.3 at a temperature of 65 ° C.

The material of the long product is a copper alloy material, the plate thickness is 0.15 mm, the number of pins is 64, and the lead width is 90 microns.

The liquid jet pump is a commercially available vertical magnet pump (YD65LC- manufactured by World Chemical Co., Ltd.).
E) was used.

The results obtained are shown in Table 1.

[0019] From Table 1, it can be seen that when the diameter of the nozzle hole is 1.0 mm, the method of the present invention is effective when the diameter of the area opening is in the range of 0.4 to 1.8 mm.

(Embodiment 2) The diameter of the area opening is set to 1.4.
mm, the diameter of the nozzle hole was 1.0 mm, and the plating was performed in the same manner as in Example 1 except that the center of the area opening and the center of the nozzle hole were offset by 0 to 0.5 mm.

The results obtained are shown in Table 2.

[0022] From Table 2, the area opening center and the nozzle hole center are 0.1
It can be seen that a good result is obtained by shifting by 0.4 mm.

(Example 3) Plating was performed in the same manner as in Example 1 except that the material of the long product was an iron alloy material, the plate thickness was 0.25 mm, the number of pins was 24, and the lead width was 200 microns.

The results obtained were similar to those of Example 1.

[0025]

According to the method of the present invention, the turbulence of the liquid and the discharge of the plating liquid in the area opening are surely achieved, and as a result, the fine plating can be easily performed and the occurrence of unevenness is prevented. it can.

[Brief description of drawings]

FIG. 1 is an external view of a nozzle plate used for conventional minute area plating.

FIG. 2 is a diagram showing a positional relationship between an area plate and a nozzle plate used for conventional minute area plating.

FIG. 3 is a diagram showing a positional relationship between an area plate used for fine area plating of the present invention and a nozzle plate.

[Explanation of symbols]

 1 --- Plating liquid jet nozzle 2 ---- Nozzle plate 3 --- Area plate 4 --- Nozzle hole 5 ---- Area plate opening 6 --- Lead frame 7 --- Center of opening 8 −−− Nozzle hole center

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Tanaka 1-6-1 Suehiro-cho, Ome-shi, Tokyo Sumitomo Metal Mining Co., Ltd. Electronic Business Division (72) Inventor Tadashi Nakano 1-6 Suehiro-cho, Ome-shi, Tokyo -1 Sumitomo Metal Mining Co., Ltd. Electronic Business Division

Claims (2)

[Claims] 1. A fine area plating method in which a center of an opening of a area plate and a center of a nozzle hole are eccentric in a method of plating a lead frame front end using an area plate and a nozzle plate. . 2. The diameter of the nozzle hole is 1.0 to 1.2 mm
The fine area plating method according to claim 1, wherein the center of the opening of the area plate and the center of the nozzle hole are decentered by 0.1 to 0.4 mm.