Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Metallic housing or support
Reexamination Certificate
2001-12-18
2003-11-18
Fahmy, Wael (Department: 2814)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Metallic housing or support
C438S125000
Reexamination Certificate
active
06649450
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method of producing an integrated circuit and to an integrated circuit per se.
In the prior art, integrated circuits are known in which a semiconductor component is fitted to a leadframe section. The semiconductor component and the leadframe section are surrounded by a plastic housing. The leadframe section has conductor tracks that pass through an outer surface of the plastic housing. Following the fitting of the plastic housing to the leadframe section and to the semiconductor component, the conductor tracks are severed, so that they terminate substantially flush with an outer surface of the plastic housing.
The step of severing the conductor tracks in the area of the outer surface of the plastic housing is also referred to as “separation”. For this purpose, punch tools are used which are constructed in such a way that the conductor tracks can be severed very close to or directly at the outer surface of the plastic housing. In some methods of the prior art, a cut is even deliberately made through areas of the plastic housing, in order to separate the relevant integrated circuits. In the case of the methods disclosed by the prior art, it is disadvantageous that the cutting tools used for this purpose, in the form of a cutting punch and a cutting dye, are subject to extreme wear. In addition, fractures on account of “chipping” and also micro cracks or micro gaps can occur on the plastic housing. As a result of such irregularities, moisture can penetrate into the inside of the plastic housing, which can lead to undesired failures, particular during the operation of leadless housing circuits. In addition, in particular in the case of leadless housing circuits produced by known methods, it is disadvantageous that these often fail during operation, since there may be unreliable solder points on the conductor track section.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method of producing an integrated circuit and an integrated circuit which overcome the above-mentioned disadvantages of the prior art methods and devices of this general type. In addition, it is an object of the invention to provide an improved leadless housing circuit.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method of producing an integrated circuit. The method includes providing a leadframe having at least one leadframe section. The leadframe section carries a semiconductor component surrounded by a plastic housing. The leadframe section has conductor tracks passing through an outer surface of the plastic housing. At least one transition area between the plastic housing and the conductor tracks is subjected to high-energy radiation such that parts of the plastic housing are removed in the transition area before performing a step of cutting through the conductor tracks for separating the integrated circuit.
According to the invention, before the step of cutting through the conductor tracks in order to separate the integrated leadless housing circuit, a step is provided of subjecting at least one transition area between the plastic housing and the conductor tracks with high-energy radiation. The step is performed in such a way that, in the transition area between the plastic housing and the conductor tracks, parts of the plastic housing are removed.
As a result of the application of the method according to the invention, a leadless housing circuit is provided which may be employed particularly advantageously. The leadless housing circuit has a semiconductor component which is surrounded by the plastic housing and with which contact can be made via conductor tracks. In this case, the conductor tracks pass through the outer surface of the plastic housing. The conductor tracks each have a dividing surface prepared by a dividing process after the preparation of the plastic housing. Following the preparation of the plastic housing, a predetermined or defined spacing is provided between each dividing surface and an area of the plastic housing surrounding the relevant dividing surface, as viewed in the plan view of the dividing surface. In this case, the designation “defined” is to be understood to mean that the spacing between each dividing surface and an area of the plastic housing surrounding the relevant dividing surface has not been produced randomly, for example as a result of fracture, but by a conscious influence. Such a conscious influence may be recognized, for example, in that in the area of each dividing surface of the integrated circuit, a spacing is provided between the dividing surface and the area of the plastic housing surrounding the relevant dividing surface if the relevant dividing surface is provided for contact to be made later.
The size of the relevant spacing between the dividing surface and the area of the plastic housing surrounding the relevant dividing surface depends on the accuracy with which a cutting tool can be guided in the area of the upper surface of the plastic housing. At present, practical spacings of the order of magnitude of 1 &mgr;m to 5 &mgr;m can be achieved. For specific applications of integrated circuits, it can also be advantageous to provide larger spacings, for example in the order of magnitude of 5 &mgr;m to 250 &mgr;m.
The leadless housing circuit according to the invention ensures low-wear fabrication with few rejects.
According to an idea on which the invention is based, the disadvantages in the methods known from the prior art may be avoided in particular if the leadframe sections provided with the plastic housing are immediately subsequently subjected to high-energy radiation in the transition area between the conductor tracks of the respective leadframe section and the plastic housing. In the process, parts of the plastic housing are removed. In the case of the known methods, the parts removed in the process come into contact with the dividing tools in a subsequent step of cutting through the conductor tracks. This was particularly disadvantageous because the fillers contained in the pressing compound for producing the plastic housing promoted wear on the dividing tools. This is particularly so when, during the preparation of the plastic housing, a pressing compound is kept in the area between two conductor tracks located beside each other. Because of the process, the pressing compound projects beyond the actual outer surface of the plastic housing and, particularly in the case of leadless housing circuits, extends in that area in which the subsequent severing of the conductor tracks is carried out. As a result of the action according to the invention on that transition area between the plastic housing and the conductor tracks, which is located between two conductor tracks lying beside each other, the undesirably projecting parts of the plastic housing are removed, so that they no longer come into contact with the dividing tools during the subsequent separation of the leadframe section. As a result, wear on the tools is reduced.
A further idea on which the invention is based, relates to the finding that the fractures at the housing edges, which occur in the case of the known method, and micro cracks or micro gaps at the housing transitions originate from mechanical stressing of the conductor tracks in conjunction with the severing of the conductor tracks. It has been shown that, as a result of the removal of parts of the plastic housing in the transition area between the conductor track and the plastic housing, the mechanical stresses can be reduced, so that an improvement in the durability of the plastic housing can be achieved in the case of the leadless housing circuit according to the invention.
In a particularly advantageous configuration of the method according to the invention, the cutting punch is specifically guided in each case such that it does not contact the plastic housing when cutting through a conductor track. As a result, wear on the cutting punch is prevented.
In the case of th
Ernst Georg
Gröninger Horst
Zeiler Thomas
Fahmy Wael
Greenberg Laurence A.
Infineon - Technologies AG
Mayback Gregory L.
Stemer Werner H.
LandOfFree
Method of producing an integrated circuit and an integrated... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of producing an integrated circuit and an integrated..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of producing an integrated circuit and an integrated... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3113669