JPH0582691A - Partial plating apparatus and leadframe for semiconductor device - Google Patents

Abstract

PURPOSE:To provide a partial plating apparatus which can partially set a plating bath lower than the entire part only with a single plating process in the same lead frame and a lead frame for semiconductor device which has formed thick plating film at the end part of an external lead and also formed thin plating film at the tie bar. CONSTITUTION:In a partial plating device of a lead frame for semiconductor device, a partial plating apparatus and lead frame for semiconductor device is characterized in that the portions other than external lead 10 is masked to form a partial plating electrolyte bath, a partial current shielding plate 7 is provided between a lead frame 4 and a plating electrode 6 within the electrolyte bath and a partial plating thickness of external lead is set lower than the other entire part. Therefore, in the same lead frame, thick plating can be done for the end part of external lead and thin plating for the tie bar only with a single plating process. As a result, high reliability of connection of external lead can be obtained, thereby peeling of plating in the resin shielding process and electrical short-circuit of external lead can also be prevented and lowering of the yield can also be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a partial plating apparatus and a lead frame for a semiconductor device.

[0002]

2. Description of the Related Art A conventional electroplating apparatus for a lead frame for a semiconductor device has a lead frame 4 as shown in FIG.
Is a device for partially plating only the outer leads 10 of the lead frame with the plating masks 2 and 9 and the presser rubbers 1 and 3. The cathode 5 is brought into contact with the lead frame and the anode 6
This is a structure in which plating is performed by passing a direct current between and. Such a partial plating apparatus is a system in which the plating solution is blown out from the nozzle 8 and the plating solution is circulated, but the plating solution is circulated almost uniformly in the electrolytic bath 13 and the plating is performed to a uniform thickness.

Therefore, in a conventional lead frame state, a lead frame in which metal plating for mounting a semiconductor device on a mounting substrate is applied to external leads (hereinafter abbreviated as PPF).
The plating thickness was almost uniform. Therefore, if the plating thickness of the external leads is increased to improve the soldering characteristics during mounting, the plating thickness of the tie part clamped by the sealing die will also be the same thickness during the resin sealing process during semiconductor device manufacturing. Is becoming

[0004]

In this conventional plating apparatus, since the plating thickness of the tie bar portion is the same as that of the external lead portion as described above, the sealing metal used in the resin sealing process during the manufacture of the semiconductor device. The plating of the tie bar portion clamped by the mold is crushed, and the plating is peeled off during the tie bar cutting / external lead bending process, which easily causes a defect that causes an electrical short circuit of the external lead. Further, the peeled plating is scattered in the manufacturing apparatus of the semiconductor device and causes a device failure, which requires more man-hours than usual in the maintenance of the manufacturing device and the operation rate is reduced.

On the other hand, when the plating thickness of the tie bar portion is set to the optimum thickness, the solderability of the external leads is deteriorated.

A first object of the present invention is to provide a partial plating apparatus capable of partially changing the plating thickness on the lead frame and continuously changing the plating thickness distribution.

A second object of the present invention is to provide a lead frame for a semiconductor device in which the thickness of the outer lead terminal portion is thicker and the thickness of the tie bar portion is thinner, and the thickness of the lead frame is continuously changed. To provide.

[0008]

The partial plating apparatus of the first invention of the present invention constitutes a partial plating electrolytic bath by masking parts other than external leads, and a partial plating electrolytic bath is provided between the lead frame and the plating electrode in the electrolytic bath. It is characterized in that a partial current shield plate is provided and the plating thickness of a part of the external leads is made lower than the whole.

In the lead frame for a semiconductor device of the second invention of the present invention, the plating thickness of the tip of the external lead terminal portion is 4 μm or more, and the plating thickness of the tie bar portion of the external lead is 3 μm or less, In addition, the plating thickness between them is characterized in that a plating film that continuously changes is formed.

[0010]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view and a plan view of a plating apparatus according to an embodiment of the present invention. The lead frame 4 sandwiched between the upper mask 2 and the lower mask 9 and the upper holding rubber 1 and the lower holding rubber 3 is connected to the cathode 5, and a DC current is passed between the lead frame 4 and the anode 6, and the plating solution nozzle 8 discharges the plating solution. Although the point of spraying into the electrolytic bath 13 to perform plating is the same as in the prior art, in the present embodiment, the current shield 7 is provided on the upper mask 2 and the lower mask 9 to prevent the flow of the plating solution sprayed from the nozzle. ing.

FIG. 2 is a sectional view and a plan view of a partial plating apparatus according to another embodiment of the present invention. In the second embodiment, the current shield plate 7 is inclined, and it is possible to further reduce the plating thickness of the narrow portion.

The distribution diagram of the plating thickness of the lead frame solder-plated by the plating apparatus of the first embodiment of the present invention is as shown in FIG. 4, and the plating thickness can be partially reduced, and the external lead tip 11 It is about 1/5 of that.

In order to improve the solderability and to stabilize the outer lead, it is desirable that the thickness of the outer lead tip is 4 μm or more, while the thickness of the tie bar of the outer lead is 3 μm or less. It is possible to solve problems caused by peeling of plating during sealing.

[0014]

As described above, the present invention continuously changes the plating thickness distribution of the lead frame by providing a partial current shield plate in the electrolytic cell in the electroplating apparatus for the semiconductor device lead frame. It has the effect of being able to.

In the lead frame of the present invention, the plating thickness can be partially reduced within the same lead frame, and the plating thickness continuously changes. This can be achieved by increasing the plating thickness in order to improve the solderability, and in the semiconductor device manufacturing process, the plating thickness is such that it is not crushed by the sealing mold in the resin sealing process. The crushed solder plating will not be clogged by the tie bar cutting and external lead bending process and the yield will be reduced due to external lead short circuit, and the solder scraps will be scattered in the semiconductor device manufacturing equipment, resulting in maintenance man-hours and equipment operation rate. It will not be lowered.

Further, as compared with a lead frame in which the mask is plated a plurality of times by changing the mask in the conventional plating apparatus, the lead frame is manufactured in a shorter delivery time, a single plating mask is required, and the jig cost is reduced. Since it can be done only once, the cost of the lead frame can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view and a plan view of a partial plating apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view and a plan view of a partial plating apparatus according to another embodiment of the present invention.

FIG. 3 is a sectional view and a plan view of an example of a conventional partial plating apparatus.

FIG. 4 is a graph showing a relationship between a plating thickness index and a measurement point of a lead frame for a semiconductor device manufactured by a plating apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1 Upper presser rubber 2 Upper mask 3 Lower presser rubber 4 Lead frame 5 Cathode 6 Anode 7 Current shield plate 8 Plating solution nozzle 9 Lower mask 10 External lead 11 External lead terminal 12 External lead tie bar 13 Electrolytic bath

Claims (2)

[Claims] 1. A partial plating apparatus for a lead frame for a semiconductor device, wherein a portion other than external leads is masked to form a partial plating electrolytic cell, and a partial current shield is provided in the electrolytic cell between the lead frame and the plating electrode. A partial plating apparatus which is provided with a plate and reduces the plating thickness of a part of the external leads from the whole. 2. The plating thickness at the tip of the external lead terminal is 4
A lead frame for a semiconductor device, characterized in that the tie bar portion of the external lead has a thickness of 3 μm or less, and the plating film between them is formed by continuously changing the plating thickness.