JPH0321045A - Lead frame and semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lead frame and semiconductor device manufacturing technology,
Furthermore, the present invention relates to a technology for manufacturing a semiconductor device using a lead frame made of Cu (copper) or the like having a high coefficient of thermal expansion.

[Conventional technology]

The lead frame is composed of a tab for mounting a semiconductor chip, tab leads extending from four corners of the tab to support the tab, and a plurality of leads with one end disposed close to the tab. Some methods are known (for example, U.S. Pat. No. 4,301,464). This type of lead frame is known as a lead frame in which the tabs are evenly supported from four directions, preventing the tabs from tilting, and in which the tab leads correspond to the four corners of the tabs. , [Problems to be Solved by the Invention] Recently, in consideration of heat dissipation from dog clippers and semiconductor chinobu, which generate a large amount of heat, lead frames with high thermal conductivity and mainly made of copper have been used. However, such a lead frame whose main component is copper has a large coefficient of thermal expansion, and if the tab is supported evenly from the four corners as in the past, it will cause problems in the assembly process, sealing process, etc. The present inventor discovered that the tab lead expands due to heat, causing displacement in three-dimensional directions such as the tab rotating or floating without stress being released.Therefore, the present inventor investigated the cause of this problem, and as shown in Figure 5, if the mechanical strength and dimensions of each tab lead T1 to T4 are the same, the stresses F, ~F, due to thermal expansion occurring there will also be the same. It has been found that a phenomenon occurs in which the tab D is displaced in three-dimensional directions.In such a case, for example, if a good connection is not obtained during wire bonding (
- Problems will occur, which will have a serious impact on the quality of semiconductor devices.

An object of the present invention is to provide a lead frame in which the tabs do not displace in the three-dimensional direction even when a material with a high coefficient of thermal expansion is used.

An object of the present invention is to provide a semiconductor device with high yield and stable quality.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, if the semiconductor chip is mounted tIt. The folding tab is supported by at least two types of tab leads with different mechanical strengths.

[Effect]

According to the above-mentioned means, stress caused by thermal expansion is released by the tab leads having weak mechanical strength, so a lead frame is obtained that can suppress displacement of the tabs in three-dimensional directions.
Moreover, semiconductor devices with high yield and stable quality can be obtained.

[Embodiment 1] FIG. 1 is a partial plan view of a lead frame according to an embodiment of the present invention, and FIG. 2 is a plan view of a semiconductor device using the lead frame of FIG.

As shown in the figure, the lead frame 1 includes a pair of parallel horizontal frames 2, 2, a pair of vertical frames 3 perpendicular to the horizontal frames 2, 2,
A rectangular tab 4 is marked in the center of the area surrounded by 3 and 3. 5A to 5D are tab leads extending from the four corners of the tab 4 and supporting the tab 4. Reference numeral 6 denotes a plurality of leads, one end of which is arranged close to the periphery of the tab 4, and the other end connected to the horizontal frames 2, 2 or the vertical frames 3, 3.

For convenience, these leads 6 are referred to as an inner lead 6A and an outer lead 6B with the typer 7 as a boundary.

By the way, in the first embodiment, the width of the first tab lead 5A is made extremely wide compared to the other second tab leads 5B to 5D. That is, since the first tab lead 5A has significantly greater mechanical strength than the other second tab leads 5B to 5D, the second tab leads 5B to 5D are bent or curved to absorb stress caused by thermal expansion. , tap 4
It is possible to suppress displacement in one-dimensional direction (direction perpendicular to the plane of the paper). 8 is a semiconductor chip, and the electrode on the semiconductor chip 8 is electrically connected to the tip of the inner lead 6A by a bonding wire 9.
0 is a plastic bungee which integrally seals the semiconductor chip 8, bonding wires 9, inner leads 6A, etc.

[Example 2] FIG. 3 shows another embodiment of the present invention, [Example 1]
The only difference is the structure of the tab leads 12A to 12D that support the tab 11, and the explanation of other parts that are the same will be omitted. 12A is a first tab lead formed with a normal thickness and width. However, the second tab lead 12
Slits 13 are formed in each of B to 12D, and their mechanical strength is relatively higher than that of the first tab lead 12A.
This means that the setting is weaker. Therefore, it is possible to suppress the second tab leads 12B to 12D, which have weak mechanical strength, from being bent (forced or curved) and causing the tab 11 to displace in three-dimensional directions.

[Embodiment 3] FIG. 4 is a partial plan view of a lead frame which is another embodiment of the present invention. This embodiment, like the other embodiments, differs only in the tab lead, so the explanation of the other identical components will be omitted.As shown in the figure, in this embodiment, the tab lead 15A to Out of 15D.
15A. Two 15B are the first tab leads, the other 15C,
15D is the second tab lead. Ding, that is, the first
Tab lead 15A, 15B Holy second tab lead 15C, 1
In order to make the mechanical strength relatively larger than that of 5D, notches 16 are provided only in the second tab leads 15C and 15D. As a result, the tab 14 and each tab lead 15A to 1
Even if stress is generated due to thermal expansion of 5D, the tab leads 15C and 15D, which have weak mechanical strength, are bent (*) to absorb the stress and suppress the displacement of the tab 14 in three-dimensional directions.

Next, the functions and effects of this embodiment will be explained.

(8) (1) At least one of the plurality of tab-supporting tab leads is composed of a first tab lead with a high mechanical strength and a second tab lead with a lower mechanical strength than the other first tab leads. As a result, the stress caused by thermal expansion is absorbed by the tab lead, which has a weak mechanical strength, so that it is possible to prevent the tab from being displaced in three-dimensional directions.

(2) By forming the first tab lead wider than the second tab lead, or by forming the wall thickness thicker, the first tab lead can have greater mechanical strength than the second tab lead. The stress caused by thermal expansion is absorbed by the tab lead, which has weak mechanical strength, and the tab is prevented from being displaced in three-dimensional directions.

(3) By providing processed parts such as grooves, slits, or notches only on the second tab lead, the mechanical strength of the first tab lead is increased compared to the second tab lead, and thermal expansion is achieved. Since the stress caused by the above is absorbed by the second tab lead, it is possible to prevent the tab from being displaced in the three-dimensional direction.

(4) Due to (1), (2), and (3), the tab position is stabilized, so the load of the bonding wire can be stably applied to the bonding surface, especially in the wire bonding process, and the bondability is improved. Accordingly, it is possible to improve the quality of semiconductor devices.

(5) By providing the first tab lead at a position opposite to the second tab lead via the tab, the stress of the first tab lead that firmly supports the tab on the frame can be reduced by providing the second tab lead located opposite to the first tab lead. It can be absorbed effectively with tab lead.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, only the second tab lead may be bent, and the other first tab leads may be formed in a straight shape.

In addition, in order to make the first tab lead more mechanically strong than the second tab lead, it may be made of a material with greater mechanical strength than the second tab lead, or may be coated or pasted with the above material. good. In addition, in this example, the tab is suspended by four tab leads, but it may be suspended by three or five or more (.Furthermore, the second tab lead may have a slit, a notch, or a cutout part mixed in. It's okay to show off.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

By supporting the tab with multiple types of tab leads with different mechanical strengths, stress due to thermal expansion is released as displacement of the tab lead with weak mechanical strength, suppressing three-dimensional displacement such as tab lifting, and producing high quality semiconductors. The device is what you get.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a lead frame according to an embodiment of the present invention, Section 2 is a schematic explanatory diagram of a semiconductor device using the lead frame of FIG. 1, and FIG. 3 is a plan view of a lead frame according to another embodiment of the present invention. FIG. 4 is a plan view of a lead frame which is an embodiment of the present invention; FIG. 4 is a partial plan view of a lead frame which is another embodiment of the present invention; FIG. be. 1...Lead frame, 2...Horizontal frame, 3...Vertical frame, 4,11. 14...Tough, 5A, 12A, 1 5
A, 1 5B... 1st tab lead, 5B to 5 D,
1 2 13-12D, 15C, 151)...Second
Tab lead, 6A...inner lead, 6B...outer lead. 7... Tie bar, 8... Semiconductor tip, 9... Bonding wire, 10... Panocage, 13... Slit, 16... Constriction part.

Claims (1)

[Claims] 1. A lead frame having a tab for mounting a semiconductor chip, a plurality of tab leads supporting the tab, and a plurality of leads arranged with their tips close to the periphery of the tab. A lead frame comprising a first tab lead having a strong mechanical strength and a second tab lead having a weaker mechanical strength than the first tab lead. 2. The lead frame according to claim 1, wherein the first tab lead is formed wider than the second tab lead. 3. The lead frame according to claim 1, wherein the first tab lead is thicker than the second tab lead. 4. Claim 1, wherein a slit, notch or notch is formed in the second tab lead, and the first tab lead has relatively greater mechanical strength than the second tab lead.
Lead frame listed. 5. A semiconductor chip, a tab on which the semiconductor chip is placed, a lead having a tip disposed close to the tab and electrically connected to the semiconductor chip, and a plurality of tab leads extending from the tab; A semiconductor device comprising a semiconductor chip, a package sealing predetermined portions of inner leads and tab leads of the leads, and outer leads of the leads extending from an outer surface of the package, wherein the tab leads are mechanically sealed. A semiconductor device comprising a first tab lead with high strength and a second tab lead with low mechanical strength. 6. The semiconductor device according to claim 5, wherein the first tab lead is formed wider than the second tab lead. 7. The semiconductor device according to claim 5, wherein the first tab lead is thicker than the second tab lead. 8. The semiconductor device according to claim 5, wherein the second tab lead is provided with a slit, a notch, or a notch, and the mechanical strength of the second tab lead is set to be weak relative to the first tab lead. .