JP5757979B2 - Semiconductor device package - Google Patents

Description

  The present invention relates to a package of a semiconductor device.

  2. Description of the Related Art A semiconductor device package in which an ultra-small electronic device such as a semiconductor chip electrically connected to a lead frame is resin-molded is known. In the structure of the typical semiconductor device package shown in FIG. 6, the semiconductor chip 101 is disposed on the central die pad portion 107 which is a part of the lead frame 102 and bonded by an adhesive resin layer. The semiconductor chip 101 and the lead frame 102 are electrically connected by bonding wires 103. A resin package body 104 made of an epoxy resin and a filler is formed to cover the semiconductor chip 101 and the lead frame 102, and the semiconductor chip 101 and the lead frame 102 are enclosed in the molded resin package body 104. A part of the lead frame 102 extends to the outside of the resin package main body 104 to become an external lead 105, which is used as a connection terminal with an external circuit.

  One of the problems that such a semiconductor device package has is that moisture enters the inside along the interface between the resin and the lead frame, causing adverse effects such as a decrease in electrical insulation. As shown in FIG. 7, moisture enters through the interface 106 between the external lead 105 and the resin package body 104. The entered moisture permeates into the inside along the lead frame 102. Due to the action of moisture, peeling occurs at the interface between the resin package main body 104 and the lead frame 102. As a result, ionic and other corrosive contaminants existing in the outside world enter. Such ingress of moisture and contaminants induces early failure due to pad corrosion of the semiconductor chip.

  As a cause of moisture intrusion at the interface between the resin and the lead frame, peeling between the resin and the lead frame is raised. When the lead frame is deformed by the stress that it receives from the usage environment, one of the factors of this peeling is that the resin cannot follow the deformation of the lead frame. The elastic modulus of the resin due to the filler (silica) contained in the resin. Because it becomes high. FIG. 8 is a schematic cross-sectional view showing the state of the filler in the vicinity of the lead frame of the prior art. The filler is distributed almost uniformly.

  In addition to poor sealing between the lead frame 102 and the resin package main body 104, there is a problem of poor adhesion at the interface between the resin package main body 104 and the back surface of the central die pad portion 107 of the lead frame 102. Such an adhesion failure causes moisture to accumulate in the peeled portion 108 generated between the lead frame 102 and the resin package main body 104 as shown in FIG. 7, particularly when the electronic device package is exposed to a humid environment. . When the electronic device package is processed at a high temperature in a processing process such as board mounting, the moisture becomes steam and causes expansion, thereby causing package cracks.

  In order to improve the adhesiveness of the resin package body to the lead frame and improve the quality and reliability of the resin package product, it has been proposed to perform various treatments on the surface of the lead frame. This type of treatment that is conventionally known is a technique in which the surface of a lead frame made of copper is treated with plasma. The existing plasma cleaning method is generally performed after the assembly of the semiconductor chip 101 and the lead frame 102 and before the molding process of the resin package main body 104.

JP-A-8-167686

  However, although the conventional plasma cleaning method is effective for the upward exposed surface, it is not very effective for promoting the adhesive force between the back surface of the central die pad portion 107 and the resin package body 104. Further, the above method does not have much effect of promoting the adhesive force between the adhesive resin layer and the lead frame. Moreover, since it is necessary to perform batch processing, plasma processing is uneconomical and difficult to apply to a continuous resin package production assembly process.

  On the other hand, the method of forming a surface treatment layer of black oxide, brown oxide, tin oxide / organosilane, etc. on the surface of the lead frame 102 is very advantageous in the treatment of the inside of the package, but has many problems outside the package. cause. For example, in the resin molding process, there is a problem that a low molecular weight portion of the molding resin flows out to the surface of the lead frame 102. This is called “resin bleed” and electrically insulates the surface of the external lead. Therefore, conventionally, in order to connect the package to a printed circuit board or the like, the resin bleed has been removed before plating the surface of the external lead with tin or solder. The resin bleed itself can be removed by ordinary chemical or mechanical methods. However, when a resin bleed occurs on a surface treatment layer such as black oxide, a film with very strong adhesion is formed by the interaction between the two, and cannot be easily removed. It is extremely difficult to completely remove the resin bleed from the surface treatment layer without damaging the lead frame or the package.

  In the semiconductor device package according to the present invention, a part of the joint surface between the lead frame and the resin package body has a mesh structure, so that the contact area of the connection surface is increased and the joint property between the lead frame and the resin package body is improved. it can. In addition, by making the network structure three-dimensional, the joining surface of the lead frame and the resin also becomes three-dimensional, so that the joining property is dramatically improved.

  In addition, by reducing the mesh of the resulting network structure to be smaller than the average particle size of the filler contained in the resin, the amount of filler reaching the surface of the lead frame is reduced, and the elastic modulus of the resin in the vicinity of the lead frame is changed to change the semiconductor. Since the resin can follow the lead frame that is deformed by the stress received from the usage environment of the device package, the adhesion is improved.

  With the formation of the semiconductor device package and the mesh structure according to the present invention, the semiconductor chip can greatly improve the bondability between the lead frame and the resin package main body. In addition, the distribution of the filler contained in the resin can be changed in the vicinity of the lead frame, and the reliability of the adhesion between the resin and the lead frame connection surface is improved. As a result, peeling of the integrally joined surface between the lead frame and the resin package main body is unlikely to occur, and it is possible to improve the quality of the electronic device package by preventing intrusion of moisture and contaminants and various adverse effects associated therewith.

Semiconductor device package as an embodiment of the present invention AA 'line sectional view in FIG. Schematic sectional view showing the state of the filler in the vicinity of the lead frame of the present invention Illustration of superposition of lead frames of the present invention Lead frame diagram showing another embodiment of the present invention Conventional technology semiconductor device package Sectional view of a prior art semiconductor device package Schematic cross-sectional view showing the filler near the lead frame of the prior art

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a first embodiment of the present invention. In the semiconductor device package 4, the semiconductor chip 1 is disposed on the die pad 9 at the center of the lead frame 2 made of a copper material, and bonded by an adhesive resin layer. The semiconductor chip 1 and the lead frame 2 are electrically connected by a bonding wire 3. A resin package body 4 made of an epoxy resin or the like is molded so as to cover the semiconductor chip 1 and the lead frame 2, and the semiconductor chip 1 and the lead frame 2 are enclosed in the molded resin package body 4. A part of the lead frame 2 extends to the outside of the resin package body 4 to become an external lead 5 and is used for connection to an external circuit. The important point is that the lead frame 2 used here has a mesh structure.

  A novolac epoxy resin can be used as the resin material constituting the resin package body 4. In addition, resin materials such as those used in the normal electronic IC package industry, such as epoxy silicon, are used. Other polyester resins and silicone resins are also used.

  The lead frame 2 has a rectangular die pad 9 that joins the semiconductor chip 1 to the center. The die pad 9 is connected to the lead frame rail by an arm.

  FIG. 2 is a schematic cross-sectional view of the lead frame section cut along AA ′. Since the lead frame 2 has the mesh structure 11 on the surface, when the resin is sealed with resin, the connection surface between the resin and the lead frame 2 is structurally firmly adhered, and the resin and the lead frame connection surface are hardly separated. .

  FIG. 3 shows a second embodiment. The network structure of the present invention has a network structure smaller than the average particle diameter of the filler 10 contained in the sealing resin. When the mesh of the mesh is smaller than the average particle size of the filler 10 contained in the sealing resin used, the mesh having a large filler diameter does not enter the mesh structure. Accordingly, the amount and diameter of the filler contained in the sealing resin can be changed near the lead frame surface, and the sealing resin elastic modulus of the lead frame network structure portion 11 can be lowered. Therefore, the sealing resin follows the deformation of the lead frame against the deformation of the lead frame due to an external force, so that the separation between the sealing resin and the lead frame connecting surface hardly occurs.

  FIG. 4 shows a third embodiment. The network structure of the lead frame has a structure in which two or more layers are stacked. As a result, even if the mesh of each layer is larger than the standard particle size of the filler 10, the mesh formed by superposition becomes smaller, and the size of the mesh can be designed for an arbitrary particle size. Furthermore, by overlapping the network structure in two or more layers, the resin enters the inside of the lead frame and becomes structurally stronger, and the bonding surface between the sealing resin and the lead frame does not easily peel off.

  FIG. 5 shows a fourth embodiment. The lead frame is wire bonded to electrically connect to the semiconductor chip. In particular, the connection part on the lead frame side is wedge bonding such that the wire is rubbed. Therefore, if there are irregularities due to the network structure at these bonding locations, the connection strength of wire bonding may be lowered in some cases. Accordingly, the connection strength of the wire bonding 3 can be maintained by flattening the wire frame bonding portion 12 of the lead frame without forming a mesh structure.

DESCRIPTION OF SYMBOLS 1 Semiconductor device 2 Lead frame 3 Wire bonding 4 Resin package main body 5 External lead 9 Die pad 10 Filler 11 Lead frame network structure part 12 Wire bonding part 101 on a lead frame Semiconductor device 102 Lead frame 103 Wire bonding 104 Resin package main body 105 External Lead 106 Interface 107 between external lead and resin package main body Central die pad portion 108 Peeling portion generated between lead frame and resin package main body

Claims (7)

In a semiconductor package having a semiconductor chip, a lead frame electrically connected to the semiconductor chip, and a resin package for sealing a part of the lead frame including the semiconductor chip with a sealing resin, the lead frame is A semiconductor device package characterized by having a network structure formed of a multi-layered structure in which a plurality of nets made of a single layer capable of entering a filler are stacked on the surface.   2. The semiconductor device according to claim 1, wherein a filler content contained in a sealing resin in the multilayer network structure is smaller than a filler content contained in a sealing resin outside the multilayer network structure. package.   2. The semiconductor device package according to claim 1, wherein the elastic modulus of the sealing resin in the multilayer network structure is smaller than the elastic modulus of the sealing resin outside the multilayer network structure.   2. The semiconductor device package according to claim 1, wherein the wire bonding connection portion of the lead frame does not have a network structure composed of the multilayers.   The semiconductor device package according to claim 1, wherein the multilayer network structure is three-dimensional.   2. The semiconductor device package according to claim 1, wherein the mesh size of each layer of the multi-layered network structure is larger than an average particle diameter of a filler contained in the sealing resin.   The mesh structure composed of the multilayers is arranged so that the meshes are shifted, so that the size of the mesh produced by superposition is smaller than the original size of the mesh of each layer. The semiconductor device package according to 1.

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