JPH0574853A - Connecting structure of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce a strain to be caused in a thermocompression bonding operation and to obtain the bonding strength, of the structure, which is more than that in conventional cases by a method wherein the shape of a bump formed on an outer lead for a TAB-system semiconductor device is formed to be a peculiar shape. CONSTITUTION:Bumps 2 on an outer lead 3 are formed to be, e.g. trapezoidal shapes or conical shapes where the area of their tip becomes smaller than the cross-sectional area of formation parts of the bumps; their initial contact area with a lead frame 4 is reduced. Thereby, a load in a thermocompression bonding operation by means of a bonding tool 6 is suppressed to be lower than that in conventional cases, a strain caused in the operation is attenuated as compared with that in conventional cases and the bonding strength, of the structure, which is more than that in conventional cases can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a semiconductor device having an improved connection method between a semiconductor element and a lead frame.

[0002]

2. Description of the Related Art Recent electronic devices are remarkably miniaturized, lightened, and highly functional, and accordingly, semiconductor devices are also small and compact.
The demands for surface mounting type and high density mounting are increasing.
Therefore, a narrow-pitch, multi-lead semiconductor device is realized by mounting a semiconductor element connected to a circuit pattern formed on a carrier film on a lead frame.

FIG. 2 shows an example of a conventional semiconductor device, which is a semiconductor device (hereinafter referred to as a TAB type semiconductor device) in which a semiconductor element is connected to an inner lead of a circuit pattern provided on a carrier film. ) Is a plan view, FIG.
(B) is the AA sectional view. The apparatus is made of a film having insulation heat resistance such as polyimide, and is provided with a large number of device holes 10 at predetermined intervals, for example, 300.
A large number of circuit patterns 16 made of copper foil or the like are formed for each device hole on the carrier film 7 on the metric side, and one end of the circuit pattern 16 is projected into the device hole to form an inner lead 8. Then, the semiconductor element is arranged in the device hole, the inner lead is connected to each electrode of the semiconductor element by a bonding tool, and the circuit pattern is cut at 11 at the position of the alternate long and short dash line. The lower surface of the circuit pattern is plated with gold, for example. Further, bumps are formed on the outer leads 3a by half etching or the like,
When joining with the lead of the lead frame by thermocompression bonding,
It helps increase the bonding strength.

To mount the TAB type semiconductor device as described above on a lead frame, the device is placed in a device hole of the lead frame and each outer lead of the device is aligned with the lead of the lead frame. The lead shape of the lead frame is plated with silver, for example. Then, when the outer lead is thermally pressed by a bonding tool having a built-in heater, each plating is melted and both are firmly thermocompression bonded.

A lead frame having a TAB type semiconductor device mounted therein is sealed from the lead frame with, for example, an epoxy resin 14 as shown in FIG.

[0006]

When the TAB type semiconductor device is mounted as described above, distortion caused by expansion and contraction caused by heat and pressure of the bonding tool is applied to both the inner lead and the outer lead of the device. There is a problem that the bumps on the outer leads may be broken from the formation portion or the inner leads may come off from the semiconductor element at the time of bonding.

Therefore, the present invention has been made to solve the above-mentioned problems, and the bumps provided on the outer leads of the TAB semiconductor device have a specific shape.
In order to obtain sufficient joint strength, the heat and pressure required at the time of joining are kept under a low load to reduce the strain generated at the time of joining,
In addition, the purpose is to obtain a bonding strength higher than the conventional one.

[0008]

A semiconductor device according to the present invention has an outer lead of a circuit pattern obtained by cutting the outer shape by connecting inner leads of a circuit pattern formed on an insulating film to electrodes of a semiconductor element. It is composed of a TAB type semiconductor device having bumps and a lead frame having a large number of leads. The outer leads of the device are respectively connected to the leads of the lead frame via the bumps and sealed with resin or the like.

[0009]

A semiconductor element, which is a TAB type semiconductor device having bumps on outer leads, is mounted in a device hole of a lead frame, each outer lead is aligned with each lead, and heat is applied by a bonding tool to join the two. .. Next, the element and the inner lead of the lead frame are sealed with a resin or the like, and cut from the lead frame to form the outer shape.

The shape of the bump provided on the outer lead of the TAB type semiconductor device used here is, for example, a pyramid or a trapezoid in which the tip area is smaller than the cross-sectional area of the forming portion of the outer lead, and at the time of joining. By reducing the contact area of the lead frame with the lead in the initial stage, the two can be bonded more firmly with a lower load than in the past.
Further, the strength of the bump forming portion with respect to the outer lead is not reduced as compared with the columnar bump in which the tip area of the bump is simply reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the essential parts of an embodiment of the present invention. FIG. 1 (a) is a side view, FIG. 1 (b) is a plan view, and FIG. 1 (c).
FIG. By making the shape of the bump formed on the outer lead of the TAB semiconductor device into a trapezoid in which the area of the tip portion is smaller than the cross-sectional area of the bump forming portion, the outer lead 3 and the lead 4a of the lead frame are initially contacted. Since the area can be reduced, the weight generated per unit area will be large even if the load is smaller than the load applied by the bonding tool conventionally required when thermocompression bonding the both. The strain generated by the load can be reduced.

If the surfaces of both the bumps 2 and the leads 4a of the lead frame are pre-plated with tin or an alloy of tin and lead, as shown in FIG. 1 (c), when they are joined by thermocompression bonding. Since the fillet is formed and the fillet is formed more easily than in the conventional case, the bonding strength higher than that in the conventional case can be obtained.

4 to 7 show the essential parts of another embodiment of the present invention, in which (a) is a side view and (b) is a plan view. Since the bump shape of these is conical,
Since the initial contact area with the lead of the lead frame is smaller than that of the trapezoid, a sufficient load per unit area can be obtained even if the load required for thermocompression bonding is further reduced. It is possible to further suppress the generation of distortion without causing the distortion.

[0014]

As described above, according to the present invention, TA
The bump formed on the outer lead of the B-type semiconductor device has a shape such as a pyramid or a trapezoid whose tip area is smaller than the cross-sectional area of the formed portion of the outer lead. It is possible to obtain the bonding strength between the outer lead of the apparatus and the lead of the lead frame more than ever before by thermocompression bonding with a lower load than before, without attenuating the strength.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a conventional TAB semiconductor device.

FIG. 3 is a diagram showing an example of a semiconductor device using a conventional TAB type semiconductor device as a semiconductor element.

FIG. 4 is a diagram showing a main part of another embodiment of the present invention.

FIG. 5 is a diagram showing a main part of another embodiment of the present invention.

FIG. 6 is a diagram showing a main part of another embodiment of the present invention.

FIG. 7 is a diagram showing a main part of another embodiment of the present invention.

[Explanation of symbols]

 1 Circuit Pattern 2 Bumps 3, 3a Outer Leads 4, 4a Lead Frame 5 Fillet 6 Bonding Tool 7 Carrier Film 8 Inner Lead 9 Semiconductor Element 10 Device Hole 11 Cutting Position 12 Test Pad 13 Sprocket Hole 14 Epoxy Resin 15 TAB Type Semiconductor Device 16 Circuit pattern

Claims (1)

[Claims] 1. A TAB type semiconductor device in which inner leads of a circuit pattern formed on an insulating film are connected to electrodes of a semiconductor element, and a lead frame having a large number of leads, and outer leads of the device and the lead frame. A semiconductor device connection structure characterized in that the two are connected to each other through a bump having a specific shape at a joint with the lead.