JPS6248386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing lead frames for integrated circuit (IC) devices. In particular, it relates to lead frames for ICs that can meet the growing demand for miniaturization and low cost of ICs in recent years.

Regarding IC packages, low-melting point glass-ceramic sealing (Cer DLP) is used for IC packages that require particularly high reliability, and plastic sealing is used for low-cost products.

Among these, the lead frame used for the former low melting point glass ceramic sealing is as shown in Figure 1.
The so-called aluminum stripe tape 3, which is a striped coating of Al2 on the iron/nickel alloy tape 1, is widely used, and most of the tapes are made by continuous rolling, and some are made by vacuum deposition. The required lead frame is made by punching it out with a press. on the other hand,
As shown in Fig. 2, the lead frame used for plastic sealing is made by forming a lead frame from iron-nickel alloy or copper alloy tape 5 by press punching or etching, and then a precious metal such as gold or silver is coated on top of the lead frame. Partially plated 4 is widely used.

However, as IC chips themselves have become larger in recent years, it has become difficult to avoid miniaturization of packages themselves due to the demand for high-density packaging, and conventional DLP
(Dual in Line Package) has reached its limit.

Under these circumstances, flat packages and chip-carrier type packages are attracting more and more attention as package methods that allow package leads to be taken out not only from two directions but from all four directions of an IC chip.

By the way, the package cost is relatively low,
When trying to adopt a flat package or chip carrier type package sealed with low-melting point glass/ceramic, which is expected to play an important role in future IC package methods due to its high reliability and A covered portion is inevitably formed, which causes major quality problems such as shortening between leads due to electromigration phenomenon and failure of solderability.

On the other hand, in order to reduce the cost of precious metal plated lead frames for plastic packaging,
There is an increasing demand for saving precious metals and even removing precious metals.

The present invention relates to the improvement of the conventional IC lead frame having such problems, and includes an Al spot 7 and a covered IC lead frame 9 shown in FIG.
The purpose of this invention is to provide a method for manufacturing the product at low cost.

The method of the present invention is to coat the entire surface of one side of the iron-nickel alloy or copper alloy tape 8 with Al using a PVD method such as vacuum evaporation, ion plating or sputtering to form a composite tape, and then form the composite tape into a desired lead frame. Press punching is performed continuously on the shape, and unnecessary parts are removed using the method described below.
It is characterized by continuously manufacturing Al spot lead frames by removing Al. Al of unnecessary parts on the punched lead frame
As shown in FIG. 5, one method for removing Al is to provide an elastic body 23 such as rubber on the endless belt 22 that matches the pitch of the lead frame, and when passing through the melting tank 21, the necessary amount of Al is removed. This method involves immersing the masking elastic body in a NaOH aqueous solution with a masking elastic body pressed against the portion, dissolving and removing Al other than the masking portion, and then passing through a washing tank 25 and a drying oven 26 and winding it onto a winding drum 27. This makes the third
The Al spot lead frame shown in the figure can be manufactured continuously.

As another method for removing unnecessary Al, it is also possible to use known resist printing.

This will be explained below using examples.

Example One side of a 42% Ni-Fe alloy tape rolled to a thickness of 0.125 mm was coated with Al to a thickness of 3 μm over the entire surface in a continuous vacuum device as shown in Figure 4 at a vacuum degree of 10 ^-5 Torr. did. In FIG. 4, 14 is a supply, 15 is a take-up, 16 is a drive roll, 17 is a water-cooled copper roll, 18 is an alloy tape, 11 is a crucible for melting Al, 12 is a mask, and 13 is a preheater. This Al-coated tape was continuously punched into the desired lead frame shape using a press.
Thereafter, the covering Al layer was removed from the required portions using a continuous partial etching apparatus shown in FIG.
That is, the required portions of Al on the lead frame sent out from the supply 19 are masked with the elastic body 23, and in the meantime, the lead frame is immersed in a 15% NaOH aqueous solution heated to 60° C. to remove the covering Al other than the required portions. Through the washing and drying process, we were able to continuously manufacture Al spot iron/nickel alloy lead frames.

In the above manufacturing process, by adding a device to the endless belt 22 shown in FIG. 5 during rotation to remove the solution between one masking and the next masking, the position accuracy of the spot Al and the surface can be improved. It is also possible to improve the condition.

As described above, by the method of the present invention, a low melting point glass/ceramic sealed flat package IC can be manufactured.
Chip carrier type IC and plastic sealing type
It has become possible to manufacture Al spot-covered lead frames used in ICs continuously and at low cost, which has had a significant effect on downsizing and lowering costs of IC packages.

[Brief explanation of the drawing]

Fig. 1 is an external view of a conventional Al stripe tape, Fig. 2 is an external view of a conventional noble metal partially plated tape, Fig. 3 is an external view of an Al spot tape made by the method of the present invention, and Fig. 4 is an external view of the method of the present invention. FIG. 5 is a conceptual diagram showing an example of a continuous vacuum evaporation apparatus used in the method of the present invention, and FIG. 5 is a conceptual diagram showing an example of the apparatus used in the method of the present invention. 1, 8, 18; Iron/nickel alloy tape, 2;
Striped Al, 3; Aluminum stripe tape, 4; Spotted precious metal plating, 5: Iron/nickel or copper alloy tape, 6; Precious metal partially plated tape, 7; Spotted Al, 9; Al spot tape, 10; Vacuum container, 11 ; Crucible, 12; Mask, 13; Preheat, 14, 19; Supply,
15; Take-up, 16; Drive roll, 17;
Water-cooled copper roll, 20; NaOH inlet/outlet, 21; Dissolution tank, 22; Endless belt, 23; Elastic body, 2
4; Pulley, 25; Washing tank, 26; Drying oven, 2
7; Winding drum.

Claims (1)

[Claims] 1. In a method for continuously manufacturing Al spot tape for IC lead frames, one side of a substrate tape is entirely coated with Al to a thickness of 1 to 10 μm, and the coated tape is press punched. A method for manufacturing Al spot lead frames, which is characterized by carrying out the following steps, and then removing parts other than the necessary parts in the next process. 2. A method for manufacturing an Al spot lead frame according to claim 1, characterized in that a PVD method is used for the entire surface coating of Al. 3 In claim 1, masking only the necessary parts with an elastic body after punching,
A method for manufacturing an Al spot lead frame characterized by immersing it in a NaOH aqueous solution to dissolve and remove Al other than the masking area. 4. The method for manufacturing an Al spot lead frame according to claim 1, characterized in that unnecessary portions of Al are removed by using resist printing in the step after punching.