JPH07115164A - Composite lead frame - Google Patents

Abstract

PURPOSE:To perform the wire bonding of a lead frame having an extra-large number of pins stably and at a high speed without deforming the inner lead parts to obtain a composite lead frame whose temperature rise in operation is suppressed. CONSTITUTION:The plate thicknesses of the inner leads 1 or the tip parts of the inner leads 1 of a lead frame are smaller than those of the other parts. The tip parts of the inner leads are arranged into zigzag formations and wide parts are provided on the tip parts. A heating plate 12 or an independent pad 2 is fixed to the thin parts of the inner leads with insulating adhesives therebetween to support the inner leads.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame suitable for an ultra-multipin semiconductor device.

[0002]

2. Description of the Related Art A semiconductor device is manufactured, for example, by mounting a semiconductor chip (hereinafter referred to as a chip) on a pad of a lead frame, welding and connecting a chip terminal and an inner lead with a thin wire, and then encapsulating with resin or ceramic. To be done.

As is well known, the semiconductor device is a core material of electronic equipment, and its technological progress is remarkable, and there is a demand for high integration, miniaturization and high speed.

The lead frame for a semiconductor device is, for example, 16
Those with 0 or more pins are manufactured by pressing or etching. In such an ultra-high pin count, the lead pitch and width are narrowed, and the inner lead tips are extremely fine in pitch and width, and are therefore often manufactured by etching.

Semiconductor devices are required to be able to exhibit their functions stably over a long period of time and to be highly reliable. On the other hand, a semiconductor device having an ultra-high pin count has a high density and a high degree of chip integration, and therefore generates a large amount of heat during use. The reliability cannot be maintained unless this is radiated to suppress the temperature rise. To prevent the temperature rise, for example, Japanese Patent Laid-Open No. 62-
As described in Japanese Patent No. 84541, there is one in which a heat dissipation plate is provided on the lower surface of a pad on which a chip is mounted, which has an effect of suppressing a temperature rise during use.

By the way, although the ultra-multi-pin lead frame is often manufactured by etching, as described above, the etching causes a side etching phenomenon and the lead width becomes narrow. In particular, since the lead width of the tip of the inner lead is narrowed and wire bonding becomes difficult, in order to avoid this, for example, the thickness of the material metal plate is partially thinned as described in JP-A-3-283644. Later, so-called half etching for forming the inner lead or the tip of the inner lead in the thin portion is performed to reduce the side etching phenomenon and prevent the lead width from being narrowed.

[0007]

The above-mentioned method has some action and effect in the manufacture of a lead frame having an extremely large number of pins, however, the inner lead or the tip of the inner lead has a reduced plate thickness and has a higher mechanical strength. It deteriorates and is easily deformed. For this reason, for example, when the wire is cut at the front end during wire bonding or after the wire is cut, the force may be applied to the tip of the inner lead and bent.

Further, although the lead width of the inner lead or the tip of the inner lead is prevented from being narrowed by the half etching, the lead width is 70 in a super multi-pin lead frame having 200 pins or more, for example. ~ 80 μm
It is difficult to secure it, and further improvement is required to make wire bonding stable and at high speed.

The portion thinned by etching has a rough plate surface and presents minute irregularities. Therefore, during wire bonding, welding connection energy may be scattered to cause a connection failure.

In the present invention, for example, even in the case of a lead frame having a super-multi-pin of 200 pins or more, a wide area is secured in the inner lead, wire-bonding can be stably and surely made, and no deformation occurs. The purpose of the present invention is to provide a composite lead frame that can prevent the temperature from rising.

[0011]

DISCLOSURE OF THE INVENTION The gist of the present invention is to provide a lead frame in which the inner lead or the tip of the inner lead has a thinner plate thickness than other portions, and the tips of the inner leads are arranged in a staggered manner. The composite lead frame has a wide width formed at its tip end, and an insulating adhesive is interposed in the thin portion of the inner lead to fix a heat sink or a separate pad to fix and support the inner lead.

[0012]

According to the present invention, since the inner lead or the inner lead tip portion is formed in a portion where the plate thickness is thinned so that the lead pitch can be made fine, and the tip portions are arranged in a staggered manner. A wide wire-bonding zone can be secured at the tip. Since the heat dissipation plate or the separate pad is provided with the insulating adhesive interposed in the thin portion where the inner lead or the inner lead tip is formed, the inner lead or the inner lead tip is fixed and reinforced. During bonding, stable welding can be performed at high speed without causing connection failure. In addition, it also has the ability to dissipate heat, increasing the reliability of the semiconductor device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings based on an embodiment. In the drawing, 1 is an inner lead, which is provided around a pad 2 on which a chip is mounted. As shown in FIG. 3, the inner lead 1 is formed in a portion 4 in which the material metal plate 3 is thinned by etching, chemical polishing, electrolytic polishing or the like.

The tip region 1a of the inner lead 1 is arranged in a staggered manner as shown in FIG. 2, and the tip region 1a is formed wide. By forming the zigzag pattern, the lead pitch can be narrowed and the number of pins can be increased.
A wide width can be formed in the tip region 1a which becomes
Even a lead frame with 0 or more pins can secure a width of 80 to 120 μm.

In this embodiment, the thinned portion 4 is formed from the middle portion of the inner lead 1 to the tip portion, but the inner lead 1 may be formed entirely.

Reference numeral 5 is an outer lead, and inner lead 1
Are lined up. Reference numeral 6 denotes a dam bar which prevents the resin from flowing out when the inside of the inner lead 1 is subsequently sealed with the resin.

A support bar 7 supports the pad 2. Reference numeral 8 is a side rail, and 9 is a guide wheel.

The lead frame L may be manufactured by an etching method, the inner lead 1 or the tip of the inner lead may be formed by an etching method, and the other lead patterns may be formed by a pressing method.

By the way, the chip 9 is mounted on the pad 2 as shown in FIG. 4, and the inner lead 1 and the chip terminal are connected by welding, for example, by an ultrasonic method, via the wire-10. The tip portion is formed in the thinned portion 4 and has a weak mechanical strength. The tip portion of the inner lead 1 is bent by the contact force at the time of welding, or the pulling force applied to the wire after cutting the wire after welding. The part may be pulled up and deformed. Further, if there is a space below the tip of the inner lead 1 due to the thinning, the welding heat does not rise during wire bonding, resulting in poor connection.

To avoid this, as shown in FIG. 4, a heat radiating plate 12 is provided below the tip of the inner lead 1 with an insulating adhesive 11 interposed to fix the tip of the inner lead. As a result, the tips of the inner leads 1 will not be deformed during wire bonding. Further, the space below the tip of the inner lead 1 is filled so that no connection failure occurs.

In this embodiment, the lead frame L is integrally formed with the pad 2. However, the present invention is not limited to this, and the pad 2 separately formed as shown in FIG. It may be provided below the tip of the lead 1 and fixed.

A double-sided adhesive tape or the like can be used as the adhesive 11 between the tip of the inner lead 1 and the heat dissipation plate 12 or the separate pad 2.

[0023]

According to the present invention, fine inner leads or inner lead tips are formed in a thinned area to form a multi-pin structure, and the tip areas of the inner leads are arranged in a zigzag manner. A wide width can be formed in the area, and the lead width of the wire bonding zone is widened.

Further, since the inner lead or the tip of the inner lead is fixed and supported by a heat sink or a separate pad with an adhesive material interposed, it does not deform, and synergizes with the wide width of the tip region, and the wire The bonding work can be surely performed at a high speed without causing a connection failure.

Since the heat sink is provided as described above,
The heat generated when a semiconductor device having a high-density chip is used is dissipated, the function is maintained for a long time, and the reliability is excellent.

[Brief description of drawings]

FIG. 1 is a diagram showing a lead frame according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing an arrangement of inner leads according to an embodiment of the present invention.

FIG. 3 is a diagram showing a cross section of a lead frame in one embodiment of the present invention.

FIG. 4 is a diagram showing a composite lead frame provided with a heat dissipation plate in one embodiment of the present invention.

FIG. 5 is a view showing a lead frame in which separate pads are combined in another embodiment of the present invention.

[Explanation of symbols]

 1 Inner Lead 2 Pad 3 Material Metal Plate 4 Thinned Part 5 Outer Lead 6 Dam Bar 7 Support Bar 8 Side Rail 9 Chip 10 Wire 11 Adhesive 12 Heat Sink L Lead Frame

Claims (1)

[Claims] 1. In a lead frame in which the inner lead or the inner lead tip has a thinner plate thickness than other portions, the tip of the inner lead is arranged in a staggered manner, and a wide width is formed at the tip to provide insulation. A composite lead frame, characterized in that the adhesive material of (3) is interposed in the thin portion of the inner lead and a heat sink or a separate pad is fixed.