JPS6190452A - Lead frame for semiconductor device - Google Patents

Abstract

PURPOSE:To enable secure automatic bonding so as to perform mounting of higher density, by a method wherein leads adjacent to each other are put in the relation of mutual engagement of wider parts and narrower parts by forming lead tips into these two parts. CONSTITUTION:In the titled lead frame having tabs for mounting and fixing semiconductor elements on and many leads with tips arranged so as to surround the tabs, the many leads are composed of two kinds of leads 3a and 3b adjacent to each other, each of which leads has the reference lead width A. The lead 3a has a wider dimension B enough for wire bonding at the tipmost part and a narrower dimension C following thereto. The lead 3b adjacent to that lead is in the relation of mutual engagement of the wider part and the narrower part, having the narrower part at the tipmost part and the wider part for wire bonding continuous thereto. Therefore, the gap dimension between adjacent leads can be kept at a fixed dimension of G.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a unit section having one tab on which a semiconductor pellet is placed and fixed, and a large number of leads arranged so as to surround this tab. Many of them are connected in a tape-like manner, and are mainly related to lead frames used for assembling resin-sealed semiconductor devices.

[Conventional technology]

When making a resin-sealed IC, as shown in Fig. 2, etching t7'c on a metal thin plate is a tab 1 for placing and fixing a semiconductor pellet formed by press working, and this tab 1. A tape-shaped lead frame is used in which a large number of unit sections are arranged in rows, each having a large number of leads 2 arranged such that their tips surround the periphery of the lead frame. and,
A semiconductor pellet is placed and fixed on the tab L, and the tip of each lead and the corresponding electrode of the semiconductor pellet are connected with a thin metal wire.
It is assembled by sealing the pellet and the tip of the lead with resin.

Incidentally, the connection between the pellet and the lead using the thin metal wire is normally made by an automatic bonder. However, during automatic bonding, it is necessary for each lead tip to have a 200 μm opening area at a defined position, which is necessary for bonding. If the tip of the lead deviates from the specified position due to deformation of the lead, or if the area of the tip of the lead is small due to high density, the automatic bonder will not be able to connect the thin metal wires properly, and the semiconductor device will fail. This will result in a fatal flaw.

[Problem that the invention seeks to solve]

In recent years, the functions of ICs have expanded, the number of leads has increased, density has increased, and miniaturization has progressed, and along with this, the leads of lead frames have become thinner. Therefore, it is very easy to deform, and in addition, when manufacturing lead frames by press punching or etching, the minimum interval (minimum punching interval) between lead tips (inner leads) is limited by the thickness of the lead frame. Therefore, a problem arises in that the yield of high-density IC assembly is reduced.

[Means for solving problems]

In order to solve the above problems, in the present invention, semiconductor pellets are
A wide part and a narrow part are formed at the lead end of the lead frame, which is arranged so as to surround the periphery of the tab to be fixed.
F49 When the leads match each other, the wide portion and the narrow portion are in a mutually intersecting relationship, and the gap between the leads is kept almost constant.

〔Example〕

Next, the present invention will be explained by examples.

FIG. 1 is a partial plan view of a lead tip portion of a lead frame according to an embodiment of the present invention. In the figure, a large number of leads are composed of two types of IJ+ leads 3a and 3b adjacent to each other, each having a standard lead width A, and the leading edge of the lead 3a having a wide dimension B sufficient for wire bonding and Next, there is a narrow dimension C, and in the adjacent leads 3b, the wide part and the narrow part are in a relationship such that the leading edge part is the narrow part, followed by the wide part to be wire bonded. Therefore, the gap size between adjacent leads is maintained at a constant size G.

〔Effect of the invention〕

In the present invention, the lead pitch PK is naturally A+G. If the wide portion B is the minimum lead width that can be bonded by an automatic bonder, and G is the minimum lead gap dimension for manufacturing a lead frame, the conventional lead pitch Po is B+G. Therefore, the reduction rate of the lead pitch P1 of the present invention with respect to the conventional pitch P is P1/P0=A+G/B+G. Here, if A = = 1.50°B = 2C, C = G, PI/P (1: hot summer 0.83), which means that the pitch is about 801 seconds compared to the conventional lead pitch. Therefore, For lead frames with the same number of leads, more reliable automatic bonding is possible, and for lead frames of the same size, a larger number of pins, that is, higher density mounting is possible.

[Brief explanation of the drawing]

FIG. 1 is a partial plan view of a lead tip of a lead frame according to an embodiment of the present invention, and FIG. 2 is a plan view of a conventional lead frame. l...T tab, 2...Lead, 3a...
...Wide lead at the tip, 3b...Narrow lead at the end, A...Standard width, B...Wide dimension, C...Narrow width dimension. , G... Gap dimension O Fig. 1

Claims (1)

[Claims] In a lead frame for a semiconductor device, the lead frame has a tab for placing and fixing a semiconductor pellet, and a number of leads arranged such that the tip end surrounds the tab, and the tip end of the lead has a wide part and a wide part. A lead for a semiconductor device, characterized in that the wide part and the narrow part of adjacent leads are in a mutually intersecting relationship, and the gap between the leads is kept almost constant. flame.