JPH022293B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a lead frame, and more particularly to a lead frame that can suitably perform partial plating only on necessary parts.

(Prior art) Plating applied to lead frames for semiconductor devices often uses expensive precious metal plating such as silver plating or gold plating, so partial plating has been developed to reduce costs. It is becoming popular. When performing this partial plating, in order to plate only the necessary areas, generally the front side of the lead frame is covered with a mask plate surrounding the plating area, and the back side is sealed to prevent the plating liquid from getting around. Plating is performed by pressing a backing plate against the plate.

FIG. 1 shows a plating apparatus in this case, which performs partial plating by spouting plating liquid from a nozzle 16 while sealing a lead frame 14 with a backing plate 10 and a mask plate 12.

(Problem to be Solved by the Invention) By the way, as shown in FIG. 2, the lead frame 14 has gaps between the lead parts 18.
Even if the mask plate 12 is pressed against the mask plate 12 for elastic sealing, effective sealing cannot be achieved up to the entrance portion of the gap. Therefore, the plating liquid leaks in the direction of arrow A through the gap, and as shown in FIG. 2b, the plating liquid protrudes to the side surface of the lead part 18 outside the plating area and is plated. Since the plating liquid in such an overhanging area is surrounded by the backing plate 10 and the mask plate 12 on both sides, plating conditions such as stirring conditions and temperature conditions are lacking, and the plating film on the overhanging area is This results in poor adhesion, and as a result, as shown in Figure c, it may peel off due to shocks during semiconductor device assembly or cyclical thermal fluctuations, leading to short-circuit accidents between the leads. ing. Also, since the plating extends beyond the plating area, more gold or silver plating film will adhere to it.
There is also the problem that cost reduction cannot be achieved.

Furthermore, when a semiconductor device is assembled, if a plating film is formed outside the resin-sealed region, a migration problem occurs, especially in the case of silver plating.

The present invention has been made to solve the above-mentioned problems, and its purpose is to suitably perform partial plating only on the necessary plating areas, and to contribute to improving the reliability of the semiconductor device. Furthermore, it is an object of the present invention to provide a lead frame that can reduce costs.

(Means for Solving the Problem) In the present invention according to the above object, in a lead frame in which the plating area portion that is not covered by the mask plate is partially plated by being sandwiched from the front side and the back side, the plating liquid is applied to the lead portion. A tie bar made of an insulating material is provided at a portion corresponding to the outer edge of the plating area to fill the gap between the opposing side surfaces of the adjacent lead part so as not to flow out into the space between the leads. .

(Function) According to the present invention, it is possible to suitably perform partial plating only on the necessary plating area, thereby reducing costs. There is no fear that the build-up film will peel off and short-circuit the lead portions, and a highly reliable semiconductor device can be provided.

In addition, since the tie bar has insulating properties, there is no need to remove the tie bar even after plating is completed, and since the tie bar is located within the gap between the lead parts, the gap between the lead parts can be ensured. Since the lead portion is held and the deformation of the lead portion is also prevented, there is a synergistic effect of reliably preventing short-circuiting of the lead portion.

(Embodiments) Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The lead frame 20 is shown in FIG. 22 is a lead part, 24 is a stage part, and 26 is a stage support bar that supports the stage part 24. The area within the broken line indicates the plating area of the part to which partial plating is applied. Lead frame 20 is formed by play machining or etching as usual.

As mentioned above, after the molding of the lead frame is completed, the part corresponding to the outer edge of the plating area is placed between the lead parts 22, between the lead part 22 and the stage support bar 2.
A tie bar 30 is provided by bridging with an insulating member such as a synthetic resin so as to fill the space between each of the opposing side surfaces of the tie bar 6.

Since the gap between the lead parts 22 and the gap between the lead part 22 and the stage support bar 26 are filled by the tie bar 30, the back side of the lead frame 20 is covered by the backing plate 10. By sealing the surface side with the mask plate 12 while leaving the above-mentioned plating area, the plating area is completely sealed, and gaps such as between the lead parts 22 in areas where plating is not required are sealed. The plating solution does not leak out, and partial plating can be performed only on the necessary areas.

Furthermore, in this embodiment, since the tie bar has insulating properties, there is no need to remove the tie bar 30 even after plating is completed, and it also has the effect of bundling the lead portions 22. In the case where a large number of lead portions 22 are provided with narrow gaps, deformation of the lead portion 22 is prevented.
This provides a synergistic effect in that short circuits between the lead portions 22 can be prevented.

The present invention has been variously explained above with reference to preferred embodiments, but the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. That's true.

(Effects of the Invention) As described above, according to the present invention, it is possible to suitably perform partial plating only on the necessary plating area, thereby reducing costs. This has the remarkable effect that a highly reliable semiconductor device can be provided without the risk of the protruding, plated film peeling off and shorting the lead portion or causing migration.

In addition, since the tie bar has insulating properties, there is no need to remove the tie bar even after plating is completed, and since the tie bar is located within the gap between the lead parts, the gap between the lead parts can be ensured. Since the lead portion is held and the deformation of the lead portion is also prevented, there is a synergistic effect of reliably preventing short-circuiting of the lead portion.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an overview of a partial plating device;
FIG. 2 is an explanatory view showing a conventional partial plating state of a lead frame, and FIG. 3 is a partial view showing an embodiment of the lead frame according to the present invention. 10...Backing plate, 12...Mask plate, 14...
... Lead frame, 16 ... Nozzle, 18 ... Lead section, 20 ... Lead frame, 22 ... Lead section, 24 ... Stage section, 26 ... Stage support bar, 30 ... Tie bar.

Claims (1)

[Claims] 1. In a lead frame where the plating area that is not covered by the mask plate is partially plated between the front and back sides, the plating liquid is applied between the lead parts.
The lead frame is characterized in that a tie bar made of an insulating material is provided at a portion corresponding to the outer edge of the plating area to fill the gap between the opposing side surfaces of the adjacent lead part so as not to flow inward.