JPH07106481A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a finger from being displaced transversely and deformed by a working force generated when the finger is connected to a semiconductor chip. CONSTITUTION:A finger 4 which is connected to an electrode for a semiconductor chip is formed of a finger base part 4b, of a connection part 4a which is connected to the electrode and of a coupling part 4c which couples the finger base part 4b to the connection part 4a. Since the flexibility of the coupling part 4c formed to be larger than that of the finger base part 4c, a working force is relaxed by the flexible coupling part, the working force is prevented from being transmitted to the finger base part, and an influence by a connection working force can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame for fixing semiconductor chips such as IC and LSI.

[0002]

2. Description of the Related Art Heretofore, a metal lead frame has been used for assembling a semiconductor device in which a semiconductor chip is integrated with a resin mold and a plurality of pins are projected. This lead frame is formed by punching out a thin metal plate with a press, etching or the like, and its shape is a rectangular tab 2 for mounting the semiconductor chip 1 as shown in FIG.
The tab leads that support the four corners of the tabs, the plurality of fingers 4 whose inner ends face the periphery of the tabs 2, the frame portion 5 that supports the outer ends of the fingers 4 and the tab leads 3, and the both end edges of the frame portion 5. The sprocket holes 6 are provided at regular intervals along the sprocket holes.

In order to assemble a semiconductor device using such a lead frame 7, the semiconductor chip 1 is first mounted on the tab 2.
After mounting, the electrodes of the semiconductor chip 1 and the inner ends of the fingers 4 corresponding to the electrodes are directly connected without using wires or wires, and then the inner region of the rectangular frame portion 5 is molded with synthetic resin to form the semiconductor chip 1 Then, the frame portion 5 is cut off to obtain a semiconductor device.

[0004]

By the way, the tip of the finger 4 of the lead frame 7 is connected to the electrode 1a of the semiconductor chip 1 by soldering or other means as shown in FIG. Is an aluminum pad formed in a thin film on the silicon 1b and is located at a position recessed from the surrounding protective film 1c.

Therefore, a bump 4a is formed at the tip of the finger 4 in order to facilitate connection with the electrode 1a. However, when a semiconductor device having a large number of pins is desired in recent years, the number of fingers similarly increases. However, the width of the finger 4 is also extremely narrow.

Moreover, since the fingers are formed by punching a thin metal plate that has been rolled in advance by pressing, etching or the like, there is a tendency that the fingers have the same thickness from the finger base portion A to the connecting portion B at the tip and have the same bending, and thus the electrodes 1a. The bonding force applied by the bonding tool at the time of the connection affects the finger base A, and the pitches between the fingers, especially the pitches between the connection parts at the tips thereof become uneven, so that highly accurate connection to the electrodes cannot be easily performed. .

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and includes a finger 4 connected to an electrode 1a of a semiconductor chip 1, a finger base 4b, and a connection portion 4a connected to the electrode. , The finger base 4b and the connecting portion 4a
And a connecting portion 4c for connecting between
c has a greater flexibility than the finger base 4b.

[0008]

[Function] Lead frame 7 having such fingers
When connecting to the semiconductor chip 1 by using, the connection part 4a at the finger tip of the lead frame 7 is first aligned so as to face the electrode 1a, and then heated and pressed with a bonding tool from the back side of the connection part 4a. Connecting. At the time of this pressurization, this pressurizing force acts so as to push and deform the connecting portion 4a in the pressing direction, and this force tries to be transmitted to the finger base 1 and exert an influence, but the connecting portion 4a and the finger base 4b Since the connecting portion 4c is disposed between the finger base portion 4b and the connecting portion 4c exhibits greater flexibility than the finger base portion 4b, the pressing force is alleviated by the flexible connecting portion 4c.
Can be reduced. This is relatively the same even when the semiconductor chip 1 side is pressed to the finger 4 side.

Therefore, even if the joint between the connecting portion 4a and the electrode 1a is inclined, the connecting portion 4 following the connecting portion 4a is formed.
c absorbs this inclination, and even the finger base portion (which is generally wider than the connection portion) is not inclined or lateral shift occurs and the pitch with adjacent fingers is not disturbed, and the connection work is facilitated. be able to.

[0010]

1 to 6 are views showing a molding process of a lead frame in an embodiment of the present invention. First, as shown in FIG. 1, a resist layer 9 having a desired pattern is formed on a substrate 8 made of a conductive metal such as stainless steel. The resist layer 9 is laminated only on the position where the lead frame 7 is not formed, and the shape of the non-resist portion 8a is a lead frame shape of a desired pattern.

Next, a peeling process is performed on the substrate 8 by using caustic soda when the resist is an alkali developing type and by using a solvent such as methylene chloride when the resist is a solvent type. Thereafter, a metal such as copper, nickel or gold is laminated on this substrate 8 by electroforming. As a result, the metal layer 10 is formed only on the non-resist portion 8a excluding the resist layer 9 as shown in FIG.

A part of the laminated body of the substrate 8 and the metal layer thus formed into a single plate is press-formed as shown in FIG.
As described above, bending processing is performed so as to project to the metal layer side. This molded portion is a tab 2 located at the center of the lead frame 7.
3 is a front end portion of the fingers 4, and FIG. 3 shows a pair of fingers 4 that face each other and extend toward the tab 2.
The fingers 4 each include a flat finger base 4b, a connecting portion 4c extending obliquely from the base 4b, and a tip 4d extending from the connecting portion 4c substantially parallel to the finger base 4b. The tab 2 is not particularly necessary.

Then, electroforming is performed again on the metal layer 10 of the laminated body deformed as described above, and the second metal layer 11 of copper, nickel or the like as shown in FIG. 4 is laminated. In this electroforming, since the connecting portion 4c is inclined with respect to the flat finger base 4b and the tip 4d, the growth rate of the electroformed metal layer 11 is slow in the connecting portion 4c.

Further, since the tip portion 4d of the finger 4 is connected to the connecting portion 4c by the thin neck portion, the current density is increased and the metal grows more in this portion. Therefore,
As can be seen from the figure, the wall thickness t2 of the connecting portion 4c is smaller than the wall thickness t1 of the finger base portion 4b and is minimum, and the wall thickness t3 of the tip portion 4d is maximum (t3>t1> t2).

Further, as shown in FIG. 5, a contact member 1 made of a material such as gold, tin or solder is provided on the tip 4d of the finger 4.
2 is applied. The contact material 12 is for improving the connection with the electrode 1a of the semiconductor chip 1, and is not particularly required, but is provided on the upper surface of the tip end portion 4d of the finger 4 in a state where the resist layer 13 covers the other portion. It may be applied or plated.

Finally, by peeling only the substrate 8 from the laminated body, the lead frame 7 having the fingers 4 as shown in FIG.
Is obtained. The tip 4d of the obtained finger 4 constitutes a bump-like connecting portion 4a having a thickness in the protruding direction thereof, and the thin connecting portion 4c provides appropriate flexibility.

In particular, by reducing the wall thickness t2 of the connecting portion 4c, it is possible to reduce the processing force at the time of joining with the semiconductor chip and prevent the finger base portion 4b from being deformed or laterally displaced. This portion serves as a buffer region. Available.

This buffer area can be obtained at the same time by the press working when forming the tip portion 4d by using the above-mentioned press working method, so that no special working is required and the working can be simplified. 7 to 10 are manufacturing process explanatory diagrams showing a modified example of the present invention.

That is, as shown in FIG. 7, the first electroforming process is performed in the state where the resist layer 9 is formed on the substrate 8 as in the first embodiment. However, the contact material 12 such as gold, tin, or solder is previously formed on the non-resist portion of the substrate 8.
Is applied or plated.

Next, as shown in FIG. 8, the entire laminated body is subjected to press working, and the portions corresponding to the fingers are bent so that the substrate 8 is projected. The bent shape is composed of the finger base portion 4b, the connecting portion 4c, and the tip portion 4d as in the above-described embodiment, and the connection portion 4a such as a bump is similarly formed by pressing on the lower surface of the tip portion 4d. To do.

Next, a second electroforming process is performed on the metal layer 10 to form a second metal layer 11 on the metal layer 10 as shown in FIG. At this time, as described above, the front end portion 4d, the finger base portion 4b, and the connecting portion 4c are formed in the order of increasing wall thickness.

Finally, the substrate 8 is peeled off to obtain the lead frame 7 having the fingers 4 having the shape as shown in FIG.
Particularly, in this case, the side of the finger 4 to be joined with the semiconductor chip remains the press shape and size of the substrate 8, so that the accuracy of the finger 4 can be improved according to the press accuracy, and the number of pins can be further increased. Can handle.

Although the two-layer metal layer formed by primary and secondary electroforming is integrally used in the above-mentioned embodiment, only the secondary electroformed metal layer is subjected to the peeling treatment between the primary electrocasting and the secondary electrocasting. It is also possible to obtain a lead frame by using, and at this time, the primary electroformed metal material can be made of an inexpensive material as compared with nickel, which is a secondary electroformed material such as copper.

Further, the substrate 8 only having the resist layer 9 formed thereon is first pressed into a desired shape, and then primary electrocasting, or primary electrocasting and secondary electrocasting is carried out. It is also possible to peel off and use the lead frame as it is.

As described above, in the above-described embodiment, since the lead frame including the fingers is basically formed by electroforming, even the lead frame having a large number of fingers which is difficult to punch by press molding is etched. It is possible to easily form the bumps at the finger tips and the flexible connecting portions supporting the bumps at the same time and easily by secondary electroforming, without using inexpensive manufacturing methods such as Is something that can be done.

[0026]

As described above, according to the present invention, the finger 4 connected to the electrode 1a of the semiconductor chip 1 is connected to the finger base portion 4b, the connection portion 4a connected to the electrode, and the finger base portion 4b. Connecting part 4 for connecting the part 4a
and the connection portion 4c has greater flexibility than the finger base portion 4b, the electrode 1a of the semiconductor device is formed.
Since the processing force at the time of connection between the finger tip and the connection portion 4a at the tip of the finger is arranged between the finger base portion 4b and the joint portions 4 and 4 and is relieved by the connection portion 4c exhibiting greater flexibility than the finger base portion 4b, It is possible to prevent processing mistakes such as lateral displacement and unevenness of the finger base 4b, and to simplify the work.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a lead frame manufacturing process in an example of the present invention, which is a resist layer forming process.

FIG. 2 is a metal layer forming process of the same manufacturing process.

FIG. 3 is a bending process of the manufacturing process.

FIG. 4 is a second metal layer forming step in the same manufacturing process.

FIG. 5 is a contact material forming step in the same manufacturing process.

FIG. 6 is a lead frame obtained by the same manufacturing process.

FIG. 7 is a resist layer forming step in the description of the lead frame manufacturing step in another example.

FIG. 8 is a press working process of the same manufacturing process.

FIG. 9 is a second metal layer forming step in the same manufacturing process.

FIG. 10 is a lead frame obtained by the same manufacturing process.

FIG. 11 is a plan view of a general lead frame using the present invention.

FIG. 12 is a cross-sectional view showing the relationship between bumps at the tips of fingers and electrodes of a semiconductor chip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor chip 1a Electrode 4 Finger 4a Connection part 4b Finger base part 4c Connection part 4d Finger tip part

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[Procedure amendment]

[Submission date] May 11, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Next, a peeling process is performed on the substrate 8 by using caustic soda when the resist is an alkaline phenomenon type and by using a solvent such as methylene chloride when the resist is a solvent type. Thereafter, a metal such as copper, nickel or gold is laminated on this substrate 8 by electroforming. As a result, as shown in FIG. 2, the metal layer 10 is formed only on the non-resist portion 8a excluding the resist layer 9 .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

Furthermore, as shown in FIG. 5, the distal end portion 4d of the finger 4 gold, tin, made of solder of a material such as contact touch material 1
2 is applied. The contact touch member 12 intended to be better the connection between the electrode 1a of the semiconductor chip 1, in a state is not particularly required coating the other portions by the resist layer 13, the distal end portion 4d upper surface of the finger 4 It may be applied or plated on.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Eiji Sakata Inventor Eiji Sakata 4680 Ikata, Katshiro-machi, Tagawa-gun, Fukuoka Prefecture Kyushu Hitachi Maxell, Ltd.

Claims (1)

[Claims] 1. A finger (4) connected to an electrode (1a) of a semiconductor chip (1), a finger base portion (4b), a connection portion (4a) connected to the electrode, and the finger base portion (4b). And a connecting part (4a), and a connecting part (4c) for connecting between the connecting part (4a) and the connecting part (4a), the connecting part (4c) having greater flexibility than the finger base part (4b).