JPH01181450A - Resin sealed semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the generation of resin cracks, by constituting the lower surface of a tab and the lower surface of a device close to an element at the central part of the tab, while constituting them as a curved surface distant from the element, or a synthesized shape of planes, or a synthesized shape of a curved surface and a plane, at the periphery. CONSTITUTION:An element 1 is mounted on a bent tab 3a via an adhesive agent 2. These are sealed with a resin 5, in the lower part of which a bent part 5a is formed. Resin cracks of lower corner part of the tab are generated by large tensile stress of the lower corner parts of the tab caused by the exfoliation of a boundary surface between the lower surface of the tab and the resin, and vapor pressure generating at this part. Since the resin 5 under the lower surface of the tab is bent, according to the same principle as the arch of a dam, the tensile stress generating in the resin 5 caused by a pressure from above is reduced. As a result, the dielectric strength is increased as compared with conventional plane type, and further the expansion of the boundary surface can be restrained, thereby preventing the resin cracks of the boundary surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a resin-sealed semiconductor device.

In particular, it relates to a structural technology for the same device suitable for preventing resin cracks that occur during solder reflow.

[Conventional technology] When an IC package is stored in a high temperature and high humidity environment, N
The resin that has stopped absorbs moisture, and during soldering, during heating (reflow), peeling occurs at the interface between the tab and the resin, and the moisture turns into steam in this space, and the resulting pressure causes the soldering to occur as shown in Figures 7 and 8. A crack 8 appears at the corner of the tab F. In order to prevent this peeling, unevenness 7, grooves, holes, etc. are provided on the surface of the tab opposite to the element mounting surface to improve the contact strength of the same interface. In addition.

Related devices of this type include, for example, Japanese Unexamined Patent Publication No. 58
-199548. 60-186044 and the like.

[Problem to be Solved by the Invention J] Although the above-mentioned prior art has the effect of restraining the displacement within the adhesive surface between the tab and the resin, it does not take into consideration the displacement in the direction of separating the two, and the tab may enter the recess. There was a problem that the resin would come off or the rurui would tear off from that part.

The object of the present invention is to overcome the disadvantages of the prior art.

The purpose is to prevent cracks caused by steam pressure.

[Means to solve the problem]

The above object is achieved by making the resin below the tab into a curved shape such that the central portion is closer to the element than the peripheral portion.

The first invention of the present application is a resin-sealed semiconductor device comprising a semiconductor element, an assembly of a tab and a lead frame for mounting the semiconductor element, and molded by sealing these with resin. The bottom surface of the tab and the bottom surface of the device are shaped close to the device at the center of the tab.

It is characterized by having a curved surface far from the element in the same periphery, a composite shape of a flat surface, or a composite shape of a curved surface and a flat surface. At this time, it is preferable that the shape of the lower surface of the tag and the lower surface of the device be one spherical surface. Further, it is preferable that the bottom surface of the tab and the bottom surface of the device have a cylindrical shape.

The second invention of the present application is a resin-sealed semiconductor device comprising a semiconductor device, an assembly of a tab and a lead frame for mounting the same, and molded by sealing these with resin. , the shape of the bottom surface is close to the element in the center of the resin on the bottom surface of the tab.

A curved surface far from the element, a composite plate of a flat surface, or a composite plate of a curved surface and a flat surface are provided in the peripheral part, and the shape of the bottom surface of the device is changed so that the central part of the plate is close to the element and the peripheral part is away from the element. Preferably a distant curved surface, a composite shape of a plane, or a curved surface.

The third invention of the present application is a resin-sealed semiconductor device comprising a semiconductor element, an assembly of a tab for mounting the same, and a lead frame, and in which these are molded to be sealed with resin. The device surface and the tab ρ are connected to the lead so that its shape is a continuous curved surface that is close to the element at the center of the tab and far from the element at the periphery, or a composite shape of flat surfaces, or a composite shape of curved surfaces and flat surfaces. It is characterized by At this time, it is preferable that the bottom surface of the device and the area from the tab to the lead be spherical, and it is also preferable that the bottom surface of the device and the area from the tab to the lead be cylindrical.

[Operation] Resin cracks at the bottom corner of the tab are a phenomenon that occurs due to excessive tensile force being generated at the bottom corner of the tab due to peeling at the interface between the bottom surface of the tag and the resin and expansion due to the vapor pressure generated in this area. It is.

By curving the resin on the bottom surface of the tab in the present invention, based on the same principle as the arch of a dam, the tensile stress generated in the resin against pressure from above is reduced, so it has higher pressure resistance than the conventional flat type. It is possible to roughly suppress the expansion of the interface. Therefore, resin cracks at the same interface can be prevented.

〔Example〕

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

Figure ag1 is a sectional view of a first embodiment of the present invention.

The element 1 is mounted on the upper surface of the curved tab 3a via the adhesive 2. These are sealed with a resin 5 having a curved portion 5a at the bottom.

FIG. 2 is a sectional view of a second embodiment of the invention.

A curved plate 6a is provided on the lower surface of the tab 3 on which the element 1 is mounted via the adhesive 2, and both are bonded together using the adhesive 2a. These are assembled into a resin 5 with a curved portion 5a at the bottom.
It is sealed by.

Note that, at this time, the adhesive 2a may be omitted and the resin 5 may be filled.

According to the above two embodiments, since the resin below the tab is curved, there is an effect of improving the strength of the resin against the vapor pressure generated at the interface between the tab and the resin.

FIG. 3 is a sectional view of a third embodiment of the present invention.

The shape from the tab 3a to the curved part 4a of the lead 4 is as follows:
It is composed of a continuous curved surface, and the element 1 is mounted on the upper surface of the tab 3a via an adhesive 2. These curved parts 5 at the bottom.
It is sealed with the resin 5 provided at-. Note that the range of the curved portion 4a of the lead 4 is not limited.

According to this embodiment, since the shape from the tab to the lead is constituted by a continuous curved surface, the range covered by the curved surface of the resin is wider than in the above-mentioned two embodiments, and the strength of the resin is improved. Can be done.

Hereinafter, FIGS. 4, 5, and 6 show the fourth and fifth aspects of the present invention.
．． A cross-sectional view of the element, adhesive, and tab of the sixth example is shown.

In FIG. 4, a bent portion 3bt having the same height as the top portion of the curved shape is provided at the periphery of the tab.

In FIG. 5, a protrusion 3C having the same height as the top of the fIj curved shape is provided on the periphery of the tab.

In FIG. 6, a flat portion is provided at the center of the tab, and only one peripheral portion is curved. In this case, the peripheral portion does not necessarily have to have a curved surface shape, but may be configured as a flat surface that is inclined toward the bottom of the device.

The above three embodiments are examples that take into consideration the accuracy of mounting the element, the improvement of the subsequent stability, and the prevention of the outflow of the adhesive.
The above-mentioned 1. Second. This is common to all of the third embodiments.

The above-mentioned tabs, the plates and leads provided on the bottom surface of the tabs, and the curved shape of the bottom surface of the resin are roughly classified into Figs. 8 and 9.
It can be divided into two types as shown in the figure.

Figure 8 shows that in a cylindrical, elongated semiconductor device (SOP, SOJ, etc.), it is possible to reduce the curvature of the device by curving it in the direction of the short side of the device. , has a significant effect.

According to this embodiment, by applying it to a semiconductor device (CMSP, PPP, etc.) having a shape relatively close to a square, it is possible to obtain an equal effect t-S on each side.

〔Effect of the invention〕

According to the present invention, it is possible to reduce the tensile stress of the resin due to the vapor pressure acting downward from the interface between the bottom surface of the tab and the resin, and to suppress the expansion of the same interface, so that it is possible to prevent the occurrence of resin cracks due to this. be.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view in the short side direction of the device according to the first embodiment of the present invention, FIG. 2 is a cross-sectional view of the second embodiment, FIG. 3 is a cross-sectional view of the third embodiment of the present invention, and FIG. 5 is a cross-sectional view of the element, adhesive, and tab of the fourth embodiment in the short side direction of the device, FIG. 5 is a cross-sectional view of the fifth embodiment, and FIG. 6 is a cross-sectional view of the sixth embodiment. 7 and 8 are cross-sectional views showing how resin cranks occur in conventional semiconductor devices, and FIGS. 9 and 10 are perspective views showing examples of other shapes of tabs applied to the present invention. be. 1... Semiconductor element + 2, 2 a... Adhesive, 3
···tab. 3a...Curved tab according to the present invention, 3b...Tab bent portion, 3C...Tab protrusion, 3d...Tab flat portion. 4... Lead % 4a... Lead curved part according to the present invention, 5... Resin, 5a... Resin curved part according to the present invention,
6a...Same curved plate, 7...Tab bottom surface unevenness, 8...
Resin crack.

Claims (1)

[Claims] 1. A resin-sealed semiconductor device comprising a semiconductor element, an assembly of a tab and a lead frame for mounting the semiconductor element, and molded by sealing these with resin. A resin-sealed semiconductor device characterized in that the shape of the lower surface of the device is a curved surface that is close to the element at the center of the tab and far from the element at the periphery, or a composite shape of a flat surface, or a composite shape of a curved surface and a flat surface. 2. In a resin-sealed semiconductor device that includes a semiconductor element, an assembly of a tab and a lead frame for mounting the semiconductor element, and is molded by sealing these with resin, a resin on the bottom surface of the tab is contained in the resin on the bottom surface of the tab. A plate with a shape close to the element at the center and far from the element at the periphery, or a composite shape of a flat surface or a composite shape of a curved surface and a flat surface is provided, and the shape of the bottom surface of the device is changed to the shape of the element at the center of the aforementioned plate. 1. A resin-sealed semiconductor device characterized in that it has a curved surface or a flat surface that is far from an element in the same periphery, or a composite shape of a curved surface and a flat surface. 3. In a resin-sealed semiconductor device that includes a semiconductor element, an assembly of tabs and lead frames for mounting the semiconductor element, and is molded by sealing these with resin, the shape of the bottom surface of the device and from the tab to the lead A resin-sealed semiconductor device characterized in that the tab has a composite shape of a continuous curved surface or a flat surface, or a composite shape of a curved surface or a flat surface, close to the element at the center of the tab and far from the element at the periphery.