JPH0429361A - Semiconductor package - Google Patents

Abstract

PURPOSE:To enable deformation of a tab to be reduced due to thermal stress on assembly, a space to be secured fully around the tab, a layout of a compact package with multiple pins to be made easily. CONSTITUTION:A flexed part 5 which becomes a thermal stress absorption part is formed at a corner part of a tab region. Namely, a tab suspension lead in a semiconductor package is connected to an opposing corner part of the tab 1, for example four corner parts, and enters the corner part, thus forming the flexed part 5 for absorbing thermal stress. Thus, it is possible to attain a sufficient thermal stress absorption for the tab suspension lead without considering space around the tab 1, thus enabling a semiconductor chip 4 to be connected to the tab 1 in the entire tab surface other than the flexed part 5 for absorbing thermal and mechanical coupling between the tab 1 and the semiconductor chip 4 can be maintained fully without interfering with thermal stress absorption function in a tab suspension lead 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin-sealed semiconductor package, and particularly to a thermal stress absorbing structure in a lead frame thereof.

[Conventional technology]

A resin package for a semiconductor integrated circuit device (IC) has a tab to which a semiconductor chip is attached, a tab suspension lead, and a plurality of leads surrounding the tab. Configure the lead frame.

When assembling a semiconductor package on such a lead frame (resin molding), the tab is deformed due to thermal stress, causing accidents such as chip cracks, poor connections, and broken wires.

In order to prevent such deformation of the tab, that is, as a means of alleviating thermal stress, Japanese Patent Publication No. 51-4905 discloses a method of forming a part of the tab suspension lead into a bent shape to provide a spring function as shown in Fig. 2. It is described by et al. With such a bent shape, even if a thermal stress that causes the tab to expand and deform during assembly is generated, this can be absorbed by the spring and the deformation can be eliminated.

[Problem to be solved by the invention]

The conventional package thermal stress absorbing means has a structure in which the tab suspension lead is bent on the outside of the tab. However, as chip sizes have increased in recent years, and on the other hand, there has been a trend to limit package sizes to smaller ones, stress is placed on the tab suspension leads in multi-pin semiconductor resin package structures with little sealing space. It is difficult in terms of space to provide a bent portion as an absorption means. In particular, when hanging a tab from the four corners of the tab, it is difficult to secure sufficient space.

The present invention is intended to solve the above-mentioned problems, and its purpose is to provide a semiconductor package structure that can absorb sufficient thermal stress even if it has only a narrow package space.

[Means for Solving the Problems] To achieve the above object, the present invention has a tab to which a semiconductor chip is attached, a tab suspension lead, and a plurality of leads surrounding the tab, and the semiconductor chip and the leads are connected to each other. The semiconductor package is partially sealed with a resin molded body, and the tab suspension lead is connected to the opposing corner part of the tab and enters the corner part to form a bent part for absorbing thermal stress. It is characterized by the presence of

In the semiconductor package of the present invention, the tab suspension leads are connected to four corners of the tab.

The present invention further provides the semiconductor package in which the semiconductor chip is connected to the tab over the entire surface of the tab other than the bent portion for absorbing thermal stress.

[Effect]

Tab suspension leads in a semiconductor package are connected to opposing corners of the tab, for example, four corners,
In addition, since it extends into a part of the corner to form a bent part for absorbing thermal stress, the semiconductor package structure is designed to allow the tab suspension lead to absorb sufficient thermal stress without considering the space around the tab. Can be provided.

Since the semiconductor chip is connected to the tab over the entire surface of the tab, except for the thermal stress absorbing bends provided at some corners of the tab, the tab and semiconductor chip can be connected to each other without interfering with the thermal stress absorbing function of the tab suspension leads. Good thermal and mechanical bonding properties can be maintained.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged plan view of essential parts of a surface mounting rc lead frame to which the present invention is applied.

1 is a tab (Cu plate) for mounting an IC chip, and 2 is a tab extending from the four corners of the tab suspension lead and connected to an outer frame (not shown).

Reference numeral 3 denotes inner lead portions of the plurality of leads, which extend from the periphery of the tab and are connected to the outer frame, respectively.

Reference numeral 5 denotes a bent portion serving as a thermal stress absorbing portion, which is formed at a part of the corner of the tab area.

4 (indicated by a broken line) indicates a semiconductor chip, which is connected to the tab at a portion overlapping with this chip.

FIG. 2 shows a conventional thermal stress absorbing structure of a tab hanging lead portion of a lead frame with reference to the present invention.

In the figure, the bent part, which is a thermal stress absorbing structure, is provided near the tab of the tab suspension lead, but it is also often provided near the outer frame, and in both cases, the thermal stress absorbing structure is It is provided by eliminating the space between the lead and the inner lead.

In contrast, in the present invention, a thermal stress absorbing structure is provided within the tab area, and as is clear from FIG. It can be used for.

5 to 7 show the form of connection between the tab and the semiconductor chip.

In FIG. 5, a hatched portion 6 is a portion where an adhesive, such as a solder layer, for chip connection is formed on the tab surface. To do this, for example, use a multi-nozzle or the like to spray liquid adhesive on the tab surface other than a portion of the corner, and then apply heat to form adhesive (solder N) 6 as shown in the figure. . In this state, chips of the same shape are stacked on the tab and connected as shown in FIG.

FIG. 7 is a sectional view taken along the line BB in FIG. 5. As shown in the figure, there is no adhesive between the chip and the tab at a corner of the chip, and the thermal stress absorbing structure portion 5 at the corner of the tab is free from the chip.

FIGS. 3 and 4 show other embodiments to which the present invention is applied, and show a portion of a tab in a lead frame.

This is an example of a thermal stress absorbing structure in which a simple cut is provided at the corner of the tab, which is selected in accordance with the size and shape of the chip to be placed on the tab.

FIGS. 8 and 9 show another embodiment of the present invention, in which a tab suspension lead is connected to the center of a pair of sides of the tab.

In this example, a pair of notches formed along the sides and part of the corner of the tab serve as a thermal stress absorbing structure.

Of these, each cut is single in FIG. 8, and double in FIG. 9, and the starting ends of the cuts in the tabs are all provided at a part of the corner.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

In resin packaged semiconductor devices, by providing a thermal stress absorbing structure inside the tab, the tab is less deformed due to thermal stress during assembly, and sufficient space around the tab can be secured, making it possible to reduce the size and increase the number of pins. Package layout is easy and highly reliable semiconductor products can be provided.

Even for packages with short tab suspension leads, the thermal stress absorbing structure allows for a longer path for moisture to enter from the outside air, and also prevents deformation of the tab in the Z direction (direction perpendicular to the plane) during assembly. can be absorbed effectively.

[Brief explanation of drawings]

FIG. 1 is an enlarged plan view of a tab and its surrounding area in a lead frame showing an embodiment of the present invention. FIG. 2 is an enlarged plan view of a portion of a tab and its surrounding area in a conventional lead frame. FIGS. 3 and 4 are enlarged plan views of a portion of a tab and a tab lead showing other examples of the present invention. FIG. 5 is a plan view showing the positional relationship between the tab and the bellet during assembly in the present invention. Figure 6 is a sectional view taken along line A-A in Figure 5, and Figure 7 is the same <
It is a BB sectional view. FIGS. 8 and 9 are plan views of tabs and tab leads in a lead frame showing other application examples of the present invention. ■...Tab, 2...Tap 3...Inner lead, 5...Thermal stress absorption structure, 4...Semiconductor chip, 6...Adhesive material. Figure 1-Tough 2-Lead for hanging the tower 5-Silent sucking hag statue Figure Figure Figure Figure Figure Figure Figure Figure Figure

Claims (1)

[Claims] 1. It has a tab to which a semiconductor chip is attached, a tab suspension lead, and a plurality of leads surrounding the tab, and a part of the semiconductor chip and the leads are sealed with a resin molding. 1. A semiconductor package, wherein the tab suspension lead is continuous with opposing corner portions of the tab and enters the corner portion to form a bent portion for absorbing thermal stress. 2. In the semiconductor package according to claim 1,
Tab suspension leads are connected to the four corners of the tab. 3. In the semiconductor package according to claim 1 or 2, the semiconductor chip is connected to the tab on the entire surface of the tab other than the bent portion for absorbing thermal stress.