JPH05315535A - Lead frame for semiconductor device - Google Patents

Abstract

PURPOSE:To enable the resin flow rate in the gate opposite side to be controlled in the higher and lower side making reference to that in an island by applying a non-conductive resin to the inner lead in the opposite side of a gate part wherein the resin is injected. CONSTITUTION:Multiple inner leads encircling an island 4 lead out the equal number of leads in four directions. A non-conductive resin tape 3 is applied to the part on the inner leads 5 in the opposite side of a gate part 7. Through these procedures, the resin flow rate in the higher and lower side can be controlled making reference to that running in the island 4 through a cavity 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-encapsulated semiconductor device lead frame (hereinafter referred to as a lead frame).

[0002]

2. Description of the Related Art A conventional lead frame, as shown in FIG. 3, includes an island 4 on which a semiconductor element is mounted, and an inner lead 5 is arranged so as to surround the island 4. As for the inner leads 5, if the same number of leads are led out in two directions or four directions by the semiconductor and are divided into the gate side and the gate facing side 2, the width of the inner leads 5 and the clearance of the inner leads 5 are designed to be substantially equal. ..

When the number of electrodes of the semiconductor element mounted on the lead frame increases, the number of inner leads 5 corresponding thereto also increases, and the tips of the inner leads 5 become finer accordingly, so that the inner leads 5 are deformed. It tends to occur. Conventionally, in order to prevent the lead from being deformed, a non-conductive resin tape 3 may be pasted on the inner lead 5, and the shape is pasted in a rectangular shape or a square shape, and the gate portion and the gate facing side are also distinguished. In this case, the resin tape 3 was formed uniformly in shape and position.

[0004]

In this conventional lead frame, the inner lead width and the gap / inner lead tape position / shape between the inner leads are designed to be substantially even on the gate side and the gate facing side, and the inner lead When a semiconductor element is mounted and placed in a mold, and resin is flowed from the gate portion 7 to the gate facing side 2 for resin sealing, the island above the island (on which the semiconductor element is mounted) and the island The volume of the resin on the lower side (back side) is different. Therefore, the speed of the resin flowing through the cavity 6 is different between the upper and lower sides with respect to the island, and there is a problem that void defects such as resin unfilling occur in the back surface side of the island having a slow resin speed in the encapsulation process.

[0005]

In the lead frame of the present invention, a non-conductive resin tape is attached to the inner lead on the side opposite to the gate portion where resin is injected. Alternatively, it is characterized in that the inner lead width on the gate facing side is thicker than that on the gate side and the gap between the inner leads is made dense.

[0006]

The present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a lead frame according to an embodiment of the present invention. Surrounding the island 4, a plurality of inner leads 5 lead out the same number of leads in four directions. Gate part 7
A non-conductive resin tape 3 is attached on the inner lead 5 on the opposite side 2. The resin tape 3 adjusts the vertical resin speed on the gate facing side 2 with respect to the island 4 flowing in the cavity 6.

Next, a second embodiment will be described with reference to the drawings. FIG. 2 is a plan view of the lead frame of the second invention. When the inner lead 3 surrounding the island 4 is divided into the gate portion 7 side and the gate facing side 2, the width of the inner lead 5 on the gate facing side 2 is thicker than that on the gate portion 7 side, and the gap between the inner leads is reduced. It's close. By this difference, the upper and lower resin speeds on the gate facing side 2 are adjusted. The second embodiment does not use the resin tape 3 as compared with the first embodiment, so that not only the cost is low, but also the inner lead 5 for large pellets on which the resin tape 3 cannot be stuck.
Suitable for lead frame 1 having a short length.

[0008]

As described above, according to the present invention, a non-conductive resin tape is attached to the opposite side of the gate portion, or the inner lead gap on the gate opposite side is made wider than that on the gate side. And the resin speed on the gate facing side is adjusted up and down based on the island. Therefore, the entrainment void defect on the back surface side of the island, which occurred because the resin speed on the upper side was higher than the resin speed on the lower side with respect to the island standard, which has been a problem until now, can be reduced.

Below, a simulation was carried out when a tape was attached to the gate facing portion this time, and the effect was confirmed. Figure 4
Is the model diagram used for this simulation. Figure 5
Is the analysis result of the simulation. The vertical axis represents the injection time, the horizontal axis represents the difference in filling rate, and the center is 0%, and the (+) direction is the ratio of the upper surface flow being executed, and the (-) direction is the ratio of the back surface flow preceding. ing. The black squares (■) in the graph represent the conventional lead frame without tape when the tape is attached. The definition of the filling rate was calculated using the following formula according to FIGS. 6 (a) and 6 (b).

Filling rate (%) = (filling length / total distance of path) × 100 Filling rate difference (%) = (filling rate of upper surface) − (filling rate of back surface) Referring to FIG. Since the resin is injected from the lower side, the resin on the back side of the island precedes at the gate part, but since the island is mounted in the middle of the cavity, the resin flow path thickness on the upper side becomes narrow, and the gate facing part On the contrary, the resin speed increases. Therefore, the resin on the upper side wraps around to the lower side, and a void defect occurs on the back surface side of the island. However, as shown by the black circles, it was confirmed that taping has the same resin filling rate on the upper and lower sides on the gate facing side, and void defects are less likely to occur. This means that the same simulation result was obtained when the inner lead width was made thicker on the gate facing side and the inner lead gap was made denser.

[Brief description of drawings]

FIG. 1 is a plan view of a lead frame according to an embodiment of the present invention.

FIG. 2 is a plan view of a lead frame according to a second embodiment of the present invention.

FIG. 3 is a plan view of a conventional lead frame.

FIG. 4 Model diagram of the plane of the lead frame used for the simulation analysis

FIG. 5 is a diagram showing analysis results.

FIG. 6 is a diagram showing the definition of an analysis method.

[Explanation of symbols]

 1 Lead Frame 2 Gate Opposite Side 3 Resin Tape 4 Island 5 Inner Lead 6 Cavity 7 Gate

Claims (2)

[Claims] 1. A resin-encapsulated lead frame for a semiconductor device, which comprises an island for mounting a semiconductor element and a plurality of inner leads arranged so as to surround the island, on a side opposite to a gate portion for resin injection. A lead frame for a semiconductor device, characterized in that a non-conductive resin tape is attached to the inner lead. 2. A resin-encapsulated lead frame for a semiconductor device, which comprises an island on which a semiconductor element is mounted and a plurality of inner leads arranged so as to surround the island, as compared with a gate portion side on which resin is injected. The lead frame for a semiconductor device is characterized in that the inner lead width on the side opposite to the gate portion is widened so that there is a close gap between the inner leads.