JP2654712B2 - High frequency heating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a high-frequency heating device.

(Prior Art) With the increase in the density and integration of a semiconductor device, the number of lead pins increases, but the package tends to be the same as before or smaller.

As the number of inner leads increases within the same area, the width of the inner leads and the distance between adjacent inner leads naturally decrease. For this reason, deformation of the inner leads due to a decrease in strength and short-circuiting between the inner leads due to the deformation may occur.

In particular, when the lead frame is formed by stamping, it is necessary to punch 0.1 to 0.12 mm width for a board thickness of 0.15 mm.Even if stamping is performed without any problem, the effect of internal residual stress is also affected. In some cases, deformation and short-circuiting may occur in a subsequent process even if only a small external force is applied.

This is also a problem when the shape is processed by etching.

However, in recent years, the size of the semiconductor device has been steadily reduced, and it is impossible to sufficiently suppress the deformation of the thin and fine inner lead.

Therefore, in order to remove such internal residual stress and harden the surface, a method has been proposed in which, after shape processing, the lead frame is heated in a neutral atmosphere furnace and gradually or rapidly cooled.

As this heating means, a high-frequency induction heating type heating device as shown in FIG. 7 is used.

This device includes a heating coil 2 wound around a dust core 1.
Thus, a predetermined space is interposed therebetween, and a lead frame as a body to be heated is caused to run in this space.

However, in such a conventional device, since the shape and dimensions (width and area) of the lead frame are partially different, uniform heating cannot be performed, and rather, disadvantages such as distortion due to thermal stress are caused. there were. Also, at most 15
There has been a problem that the temperature can be raised only to 0 to 200 ° C., and sufficient surface hardening cannot be performed.

Further, there is a problem that it takes a long time to raise the temperature, the thermal efficiency is poor, and even when the twist occurs, the material is cured as it is.

(Problems to be Solved by the Invention) As described above, with the increase in the degree of integration of the semiconductor device, the lead width and the interval are decreasing, and sufficient internal residual stress is removed, deformation such as torsion is corrected, and surface hardening is performed. There has been a demand for a heat treatment method for performing the above.

This has been a problem not only when forming a lead frame, but also when forming other devices that require fine processing.

The present invention has been made in view of the above circumstances, and has as its object to provide a small-sized heating device capable of efficiently and uniformly heating a minute-sized object while maintaining its shape with high accuracy.

[Configuration of the invention]

(Means for Solving the Problems) In view of the above, the heating device of the present invention includes a heating unit configured by bringing a heating plate made of a ferromagnetic material into contact with one surface of an induction heating coil. Further, a predetermined position of the continuous lead frame as a body to be heated is pressed to perform heating.

Desirably, first and second heating means, which are formed by abutting a heating plate made of a ferromagnetic material on one surface of the induction heating coil, are disposed opposite to each other, and the first and second heating means are arranged opposite to each other. At least one of the heating plates is configured to be pressed against a predetermined position of a continuous lead frame as a body to be heated to perform heating.

(Function) According to the present invention, since a heating plate made of a ferromagnetic material is pressed against a predetermined position of the lead frame to perform heating, heating can be performed efficiently, and the width, Even for a lead frame having a local area or the like, uniform heating can be performed. In addition, since heating is performed in a fixed state, deformation is small, and even if there is a twist, correction is performed, and a good shape can be obtained.

In addition, since the heating can be efficiently performed by contacting the heating plate heated by the high-frequency heating, the heating area can be reduced, and a small and highly reliable heating device can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view showing a high-frequency heating device according to an embodiment of the present invention.

This heating device intermittently interposes a lead frame F having a shape processed between an unwinding device (not shown) having a tension adding function and a winding device (not shown) having a tension adding function. While carrying, high frequency heating is performed on a predetermined area of the lead frame,
It is composed of a high-frequency heating unit 10 and a cooling unit 20.

As shown in FIG. 2, a high-frequency heating unit 10 includes an induction heating coil 2 made of a hollow rectangular copper wire wound around a dust core 1 and a heating plate 4 made of a Cr ferromagnetic material. And a pressing plate 6 disposed opposite to the heating unit 5 and configured to be able to press the lead frame in the direction of the heating unit 5 by the actuator 21. The pressing plate 6 is moved in the direction of the heating plate 4 of the heating means, and is heated while pressing an area other than the side rails of the lead frame.

Further, the cooling unit is disposed opposite to the first cooling plate 20a and the first cooling plate 20a.
A second cooling plate 20b configured to be able to be pressed in the direction of 20a, and moving the second cooling plate 20b in the direction of the first cooling plate 20a to remove the heated area of the lead frame. It is configured to cool while pressing.

Here, 7 is a guide pin, 8 is a mask plate for heating only a desired area, and 9 is a support plate.

Next, a method for manufacturing a lead frame using this heating device will be described.

3 (a) to 3 (e) are views showing the steps of manufacturing the lead frame according to the embodiment of the present invention.

First, as shown in FIG. 3 (a), a strip material is processed by a stamping method, and the tip of the inner lead 24 facing the die pad 22 is slightly connected to the adjacent inner lead by the connecting piece T. Mold.

Next, after performing a coining process to secure the flat width of the tip of the inner lead, the lead frame F is mounted on the high-frequency heating device shown in FIG. Here, the thickness of the tip of the inner lead after coining is 0.12 mm.

Then, heating is performed while the lead frame F is intermittently conveyed between an unwinding device having a tension adding function and a winding device having a tension adding function. Here, while the pressing plate is pressed against the heating plate by the actuator 21, heating is performed at 600 ° C. for 1 second by high-frequency heating to heat the heating plate, and the area excluding the side rails of the lead frame via this heating plate. Heat. Thereafter, the pressing of the pressing plate is released by the actuator 21, the one-pitch lead frame is transported, transferred to the heating section cooling section, and rapidly cooled by the cooling section 20. At this time, in the high-frequency heating unit 10, heating of adjacent units is performed in parallel. FIG. 3 (b) shows a processing region R by this high-frequency heating.

Thereafter, as shown in FIG. 3 (c), through a predetermined plating step, taping step, and the like, the connecting piece is punched out, and the tip of the inner lead is separated to complete the lead frame.

After the semiconductor chip is mounted on the die pad 22 of the lead frame, the semiconductor chip and the lead frame are electrically connected by wire bonding.

Then, a semiconductor device is completed through a resin sealing step, a tie bar cutting step, and an outer lead forming step.

The lead frame thus formed is hardened by quenching using heating, internal stress due to shape processing is removed, deformation such as torsion is corrected, and extremely high precision is achieved. Since the leading ends of the leads can maintain a good positional relationship with each other, not only short-circuiting between the leads but also short-circuiting with the bonding wire is prevented, and the reliability is extremely high. Further, the thickness of the lead frame may be 0.15 mm or less.

In addition, since the connecting piece is removed after reinforcement with an insulating tape, the inner lead can have a reduced lead width at the tip. As a result, the tip of the inner lead can be brought closer to the die pad, the amount of bonding wire used can be reduced, and the manufacturing cost can be reduced. Furthermore, the bonding wire can be shortened, and a short circuit is prevented.

Furthermore, in the above-described embodiment, the lead frame was molded in a state of being connected by the connecting piece, and after attaching the insulating tape, the connecting piece was removed, but the lead frame was molded without leaving the connecting piece. Needless to say, this is also applicable.

In addition, in the above embodiment, the lead frame of the wire bonding type has been described, but the present invention is also applicable to a lead frame of the direct bonding type.

In the above-described embodiment, the high-frequency heating unit 10 is provided with a heating means only on one side and a pressing plate on the other side. However, as shown in a modified example in FIG. Heating means 5a and 5 constituted by bringing a heating plate 4 made of Cr ferromagnetic material into contact with one surface of the turned induction heating coil 2
b are disposed opposite each other, and these two heating means 5a,
The lead frame may be sandwiched by 5 and heated while being pressed.

In addition, as shown in FIG.
The induction heating coil 2 may be wound directly around the heating plate 4 made of a ferromagnetic material, and the first and second heating means 5a and 5b may be provided.

In addition, as shown in FIG. 6A, two high-frequency heating units 10a and 10b may be arranged at a predetermined pitch in the running direction of the lead frame. The heating area at this time is shown in FIG. Here, only the die pad and the inner lead are heated.

In the above embodiment, Cr was used as the heating plate.
In addition, a magnetic material such as nickel may be used.

In addition, in the above-described embodiment, the shape processing of the lead frame has been described. However, it is needless to say that the present invention is not limited to the lead frame and can be applied to other devices.

〔The invention's effect〕

As described above, according to the present invention, the heating plate made of a ferromagnetic material is pressed against a predetermined position of the object to be heated, and the heating is performed. It is possible to perform uniform heating even on an object to be heated whose width, area, and the like are locally different. In addition, since heating is performed while pressing, shape correction can be performed, and high-precision shape processing can be performed.

[Brief description of the drawings]

FIG. 1 is a view showing a high-frequency heating apparatus according to an embodiment of the present invention, and FIG.
FIGS. 3 (a) to 3 (c) are views showing a manufacturing process of a lead frame according to the embodiment of the present invention, and FIGS. FIG. 6 (b) is a view showing a processing area in the apparatus of FIG. 6 (a), and FIG. 7 is a view showing a conventional heating apparatus of another embodiment of the present invention. It is. F ... lead frame, 1 ... dust core, 2 ... induction heating coil, 4 ... heating plate, 5 ... heating means, 7 ... guide pin, 8 ... mask plate, 9 ... support plate, 10 ... ... High frequency heating section, 20 ... Cooling section, 20a ... First
Cooling plate, 20b ... second cooling plate, 21 ...
Actuator, 22 ... die pad, 24 ... inner lead, 28 ... outer lead, 29 ... support bar, T
…… Connection piece.

Claims (2)

(57) [Claims] 1. A heating means comprising a heating plate made of a ferromagnetic material in contact with one surface of an induction heating coil, wherein the heating plate of the heating means is pressed against a predetermined position of a continuous lead frame, A high-frequency heating device configured to perform heating. 2. A heating apparatus comprising a heating plate made of a ferromagnetic material abutting one surface of an induction heating coil, and first and second heating means arranged opposite to each other. A high-frequency heating apparatus characterized in that heating is performed while pressing a predetermined position of the continuous lead frame with a heating plate of the means.