JPH02860B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead frame for an IC, and particularly to the structure of a lead frame for a glass-sealed IC.

For glass-sealed ICs, for example, a lead frame with multiple leads formed by press processing using 42 alloy conditions is welded to a ceramic substrate coated with glass, an IC element is fixed to this, and then the inner layer of the lead frame is The lead tip and the electrode of the IC element are made of aluminum.
It is assembled by connecting with wires. The Al wires are usually connected using an automatic bonder, and the important quality of the lead frame welded to the ceramic substrate is that the tips of each inner lead are fixed in a predetermined position.
However, as shown in Fig. 1, in the conventional lead frame, each lead 1 is supported at only one point by the external connector 2 and extends to the center, and is bent at an angle of approximately 90° along the way. Because it is applied,
Each lead is easily deformed and the position of the lead tip is easily changed. This deformation of each lead is caused by the internal stress of the material being deformed by punching in press working, and is also caused by handling work in the subsequent assembly process.

Usually, the tips of each inner lead are arranged at a predetermined pitch in a rectangular shape, as shown in FIG. However, if the deformation occurs as described above, the inner lead tip position 3a will move to the position 3b shown by the broken line. As a result, automatic bonder
The Al wire connection is not made correctly in the center of the lead,
This causes a fatal defect as an IC.

In particular, with the recent expansion of IC functionality, there is a demand for ICs with a large number of leads, and each lead is thinner.
Also, since it is longer, the tendency for it to deform is even greater.

Therefore, the purpose of the present invention is to ensure that the automatic bonder
It is an object of the present invention to provide a lead frame in which the position of the tip of an inner lead does not change in order to enable Al wire connection.

Examples according to the present invention will be described below.

FIG. 3 is a plan view of the central portion of the lead frame according to the embodiment of the present invention.

The first feature of the present invention is that a small piece 5 having an outer circumferential line matching a part of the lead tip shape is combined in the center of the conventionally shaped lead frame shown in FIG.

Normally, lead frames are manufactured using a progressive press mold, but the shape of the central part of the inner leads at the intermediate stage of progressive feeding is as shown in Figure 5, with the tips of each inner lead connected at the center. The inner lead is formed by pulling out the central connecting portion at the position of the straight line 6 in the step , but in the lead frame according to the present invention, for example, as shown by the broken line 7, the central connecting portion is cut in a shape that forms a concave portion. By releasing it, an inner lead is formed. The small piece 5 of the central connection part that has been cut here is not pulled out, but is pushed back into the original plate by the spring force embedded in the lower mold as the upper mold of the press rises after cutting. 5 and the inner lead 3 are combined and held together, so that the small piece 5 does not come off. This push-back is a technique often used in current press processing technology.

FIG. 4 is a sectional view of a lead frame according to an embodiment of the present invention welded to a ceramic substrate coated with glass. As described above, the small piece 5 and the inner lead tip 3 are held together, so that each inner lead tip is welded to the ceramic substrate with the positional dimension of each inner lead tip remaining the same as the press punching dimension. In this state, the small piece 5 in the center can be easily removed by pulling it upward using the small hole 8, for example.

As a result of the above, it is possible to obtain a lead frame in which there is no change in the position of the tip of the inner lead, that is, a lead frame that can be reliably connected with an automatic bonder.

In addition to the above example, the unbroken shape of the inner lead can be easily considered to be a tapered shape 9, a reverse tapered shape 10, a V shape outside the central connection part, etc. as shown in FIG. In the case of , pushing back after cutting is also an important point.

A second feature of the present invention is that the central small piece 5 is provided with a hook portion and a cutout portion as shown in FIG. In addition, in FIG. 7, the locations where the small pieces of material are present are indicated by diagonal lines sloping upward to the right. The purpose of these is to remove small pieces 5 from the lead frame crimped onto the glass substrate.
This is to make it easier to remove when removing.

The hooking portion may have any shape as long as it can easily catch an external jig or tool, such as a small hole 8 or a corner 12 formed on a V-shaped bent portion. Furthermore, when the small piece 5 is pulled by the hook parts 12 and 8, the small piece is easily bent from the center, causing a deformation effect between the part where it is combined with the inner lead and the hollow part 13. The inwardly directed horizontal stress component generated at this time results in curvature, allowing the small pieces to be easily removed.

According to the present invention, since the inner lead tip position accuracy is extremely high, no misalignment occurs in the automatic bonder. Further, since no deformation occurs during the handling of the lead frame from the lead frame manufacturing process to the welding process to the ceramic substrate, there is an advantage that work efficiency is greatly improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional lead frame with some parts omitted, FIG. 2 is a plan view of the center of the conventional lead frame, and FIG. 3 is a plan view of the center of the lead frame according to an embodiment of the present invention. 4 is a sectional view of a lead frame according to an embodiment of the present invention welded to a ceramic substrate, FIG. 5 is a plan view of a conventional lead frame in an intermediate state of manufacture, and FIG. 6 is a diagram showing another embodiment of the present invention. FIG. 7 is a plan view of the central part of a lead frame for illustrating an example, FIG. 7 is a plan view showing the shape of a small central piece of an embodiment of the present invention, and FIG. 8 is a side view of the same as FIG. 7. In the figure, 1...Lead, 2...External connection band, 3a...Tip position, 3b...Position indicated by broken line, 5...Small piece, 7...Dotted line, 8...Small hole in hook part, 9... Tapered shape, 10... Reverse tapered shape, 1
2... Corner of the hook.

Claims (1)

[Claims] 1. In a lead frame used in a glass-sealed IC, the tips of multiple inner leads are made of the same thickness and material as the inner leads throughout the thickness direction, and are compatible with the shape of the tips. However, small pieces cut from the tip are assembled, and the small piece is further provided with a hollowed out part that weakens the bending strength of the small piece itself and a hook part used to remove the small piece. Features of IC lead frames.