JPH0730687Y2 - Bump plating machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a plating apparatus for performing bump plating on IC electrodes on a wafer.

[Outline of device]

The present invention relates to an improvement of a plating apparatus that suppresses variations in plating of bump plating (gold bumps, solder bumps, etc.) within a wafer and performs bump plating with good yield. The wafer fixing three-point electrode jig of the plating equipment is formed of a material having spring properties, the part supporting the outer periphery of the wafer from below, the part allowing electrical connection from the wafer side surface (thickness direction), and cup-shaped plating of the wafer The wafer is fixed by a jig that is composed of a part that is pressed down by the spring force toward the center of the tank and an electrode terminal that can be screwed to the outer edge of the cup-shaped plating tank. It is characterized by being.

[Conventional technology]

Conventionally, the plating tank is cup-shaped and the plating solution is supplied from the lower part and overflowed from the upper part.The anode is placed in the lower part of the cup-shaped plating tank, and the wafer is coated with a three-point electrode jig at the liquid surface where the plating solution overflows Fix the electrical connection to the IC electrode on the wafer with the contact pin connected from the top to the electrode terminal part of the three-point electrode jig that becomes the anode and cathode formed on the outer edge of the cup-shaped plating tank. In the bump plating apparatus, the wafer fixing structure is as shown in FIG. 3 in which an electrode jig is formed by bending a wire having rigidity to some extent from an electrode terminal portion fixed to the outer edge of the cup-shaped plating tank with a screw. It is introduced into a cup-shaped plating tank, its tip is sharpened, and parts other than the electrical connection parts are masked. The wafer is surrounded by the three tip parts of such an electrode jig. Supported in the near surface, and the tip portion has been a structure in which electrical connection is made in the form of break through the resist of the wafer surface.

[Problems to be solved by the invention]

In such a wafer fixing structure, the tip of the electrode jig is located on the surface of the wafer to support the wafer and make an electrical connection. Therefore, the IC chip in the portion hit by the tip is definitely defective and the yield is increased. In the case of plating that not only drops but also bubbles occur from the cathode during plating, bubbles are violently generated at this tip, which tends to cause variations in plating thickness, etc.
Further, since the tip portion of the wafer is located on the surface inside the wafer, it affects the current distribution, the plating solution, and the flow of bubbles, causing similar variations.

[Means for solving problems]

The present invention solves the above-mentioned problems, suppresses the variation of plating, and performs bump plating with high yield. Therefore, the wafer is electrically connected from the side of the wafer, and a wafer fixing structure that prevents obstacles on the wafer surface as much as possible. The three-point electrode jig is made of a material having a spring property, the part supporting the outer periphery of the wafer from below, the part allowing electrical connection from the side surface of the wafer, and the spring of the wafer in the center of the cup-shaped plating tank. The structure is composed of a portion to be pressed down by force and an electrode terminal portion that can be screw-fixed to the outer edge of the cup-shaped plating tank, and the portions other than the electrical connection portions are masked with plating resistance to fix the wafer.

[Action]

By doing so, the electrical connection portion that strongly generates bubbles is kept away from the wafer surface, there is no sharp tip that pushes the wafer surface, and the flow of the plating solution by the electrode jig and the current distribution are significantly improved.

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

〔Example〕

The cup-shaped plating tank is generally used, which has a plating jet port in the lower part, and has six triangular pillars and four square pillars protruding from the overflow part in the outer peripheral part of the upper part. One of the pillars is used as an anode electrode terminal, and three years is used as a cathode electrode terminal. In this embodiment,
A case where the pillar is a triangular pillar will be described below as an example.

First, as the material used for the electrode jig, a plate material such as SUS, Be-Cu, phosphor bronze having a spring property is used, which is processed by photo etching or press punching,
Bending is performed to form an electrode jig. A plate thickness of 0.5 to 1.5 mm at this time is suitable for obtaining a spring force for fixing the wafer.

The shape of this electrode jig will be described in detail with reference to FIGS. 2 and 4.

First of all, the outer peripheral portion of the wafer is supported from below so that it has a portion that does not fall into the plating tank. The support length at this time does not affect the flow of liquid during plating,
3mm or less is recommended so that it is not related to the yield of chips.

Secondly, it is a part to enable electrical connection from the side surface of the wafer, but this does not hinder the flow of the plating solution and ensures that the cross section in the thickness direction contacts the side surface of the wafer in order to ensure contact. To do.

Thirdly, it is a part for pressing the wafer toward the center of the cup-shaped plating tank with a spring force. This is a 4-inch wafer with a pattern of about 2 to 3 mm in length, and the spring force of the warp is used. And press it down.

Finally, the electrode terminal part wraps the triangular prism from the top,
It is fitted into the upper part of the triangular prism, and has a hole so that the upper part can be fixed with screws.

As the electrode jig having the above-mentioned basic structure, one having a shape as shown in FIG. 4 was produced.

This is bent, and the surface that is fixed to the triangular prism with the screw of the electrode terminal part and the minimum part necessary to enable electrical connection with the wafer side surface are used. An electrode jig was prepared by masking with a plating masking agent.

Three such electrode jigs were used, screwed to a cup-shaped plating bath as shown in FIG. 1, and the wafer was set in the form shown in FIGS. 1 and 2.

The wafer was fixed in a fixed state by spring force from three points, the state of rest was good, and the electrical connection was good.

In this state, bump plating of gold, solder, etc. was performed, and the plating quality was confirmed. As a result, a high yield could be achieved without the conventional defects.

[Effect of device]

As described above, according to the present invention, since no electrical connection is made on the wafer surface, the IC chip is not damaged and the yield is not reduced.

Further, since the electrical connection portion is moved from the wafer surface to the wafer side surface, there is no influence of violent bubbles, and variations in plating thickness and the like can be reduced.

Furthermore, by supporting the wafer at the outermost periphery, which is not related to the IC chip, the current distribution, the plating solution, and the flow of bubbles can be improved, and the variation in plating can be reduced.

Regarding the shape of the electrode jig, which is the main point of the present invention,
It goes without saying that various forms can be made without particular attention to the embodiment as long as it has the basic structure as described above.

[Brief description of drawings]

FIG. 1 is a plan view showing a wafer fixing structure of the present invention, and FIG.
FIG. 3 is a partial sectional view thereof, FIG. 3 is a partial sectional view showing a conventional wafer fixing structure, and FIG. 4 is a schematic plan view of an electrode jig used in the present invention.

Claims (1)

[Scope of utility model registration request] 1. A plating bath having a cup shape, in which a plating solution is supplied from a lower portion and overflowed from an upper portion, an anode is arranged in a lower portion of the cup-shaped plating tank, and a wafer is a three-point type at a liquid surface portion where the plating solution overflows. Fix with an electrode jig,
In a bump plating device for IC electrodes on a wafer having a structure in which electrical contact is made by connecting contact pins from the top to the electrode terminals formed on the outer edge of the cup-shaped plating tank, the wafer fixing electrode jig is It is formed of a material having a spring property, and as its constitution, a portion that supports the outer periphery of the wafer from below, a portion that allows electrical connection from the side surface of the wafer, a portion that presses the wafer toward the center of the cup-shaped plating tank with a spring force, and A bump plating apparatus characterized in that a wafer is fixed by a jig which is composed of an electrode terminal portion which can be screw-fixed to an outer edge portion of a cup-shaped plating tank and which is masked with plating resistance except for an electrical connection portion.