Registers – Records – Conductive
Reexamination Certificate
2002-02-26
2003-05-06
Lee, Michael G. (Department: 2876)
Registers
Records
Conductive
C235S383000, C257S778000, C257S737000
Reexamination Certificate
active
06557769
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a smart card module including a semiconductor chip that is electrically conductively contact-connected to a connection plane in which contact areas are formed. At least one side of the semiconductor chip is provided with an electrically insulating protective layer. Pads are formed on the surface of the protective layer that is remote from the semiconductor chip, and these pads are electrically conductively connected to the contact-connection points of the semiconductor chip. The semiconductor chip is arranged with the pads first on the connection plane and is electrically conductively contact-connected to the contact areas via the pads. Moreover, the invention relates to a method for producing such a smart card module, and also to a smart card including such a smart card module.
Smart card modules usually include a carrier, for example a laminated plastic film or a metallic connection lead frame, on which a semiconductor chip is fixed. The conductive layers or constituents of the carrier are patterned to form individual contact areas that can be tapped using a card reader. The form and size of the contact areas, which are usually arranged in a connection plane, generally depend on particular standard specifications such as, for example, ISO Standard 7816. In conventional smart card modules, semiconductor chips and contact areas are electrically contact-connected using bonding wires that are led from the contact-connection points of the semiconductor chip to the connection points of the contact areas. As an alternative, the semiconductor chip can be applied using flip-chip technology.
In order to protect the chip and the connections to the contact areas, a layer made of epoxy resin, thermosetting plastic, or the like is applied above the chip and the connecting points. The finished smart card module, which generally has a component height of at least 500-600 &mgr;m, is finally implanted into the card carrier of a smart card.
Published German Patent Application DE 197 08 617 A1 discloses a smart card module of the type mentioned in the introduction in which the semiconductor chip is not incorporated as an initially “naked” chip (as described above), and housed only afterward, that is to say in the smart card module, but rather is incorporated as a so-called die size package, nowadays usually called a chip size package (CSP). These packages are already provided with a protective layer and with pads and permit smaller module thicknesses. In this case, for mounting, it is also known to use a connection lead frame strip from which the individual smart card modules are separated only after the positioning, placement, and contact-connection of the die size packages—evidently assumed to be finished—on the respective contact areas.
There are many options for producing and constructing such specially housed chips or for integrating their production into the mounting sequence of the smart card modules, the advantages and disadvantages of these options have to be balanced. In the course of the increasingly greater functional diversity and the chips that thus become ever larger, not only the demands for smaller module thicknesses increase, but also the demands placed on the mechanical robustness. With CSP-like housings becoming larger, which would be coupled to a connection lead frame strip during production, the utilization of the carrier strip and the injection machine would inevitably also become poorer.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a smart card module, a smart card with the smart card module, and a method for producing the smart card module which overcome the above-mentioned disadvantages of the prior art apparatus and methods of this general type.
In particular, it is an object of the invention to provide a smart card module of the type mentioned in the introduction that can be produced simply and effectively and that has small component dimensions. The semiconductor chip should also be well protected against mechanical damage and chemical influences. The invention also includes a method for producing such a smart card module in a fabrication-optimized manner. Moreover, the smart card module should be able to be incorporated into a smart card.
With the foregoing and other objects in view there is provided, in accordance with the invention, a chip element including a semiconductor chip for electrically conductively contact-connecting a connection plane in which contact areas are formed. The semiconductor chip has sides and contact-connection points. The chip element includes an electrically insulating protective layer located on at least one of the sides of the semiconductor chip. The electrically insulating protective layer has a surface that is remote from the semiconductor chip. The chip element includes pads formed on the surface of the electrically insulating protective layer that is remote from the semiconductor chip. The chip element includes flip-chip bumps that electrically conductively connect the pads to the contact-connection points of the semiconductor chip. The semiconductor chip and the electrically insulating protective layer can be configured such that the pads are first on the connection plane and such that the pads can electrically conductively contact-connect the semiconductor chip to the contact areas. The electrically insulating protective layer is applied only around the semiconductor chip. The flip-chip bumps extend through the electrically insulating protective layer. Each one of the flip-chip bumps has an end that is remote from the semiconductor chip. The end of each one of the flip-chip bumps forms a pad lying approximately plane-parallel in the surface of the electrically insulating protective layer that is remote from the semiconductor chip. The electrically insulating protective layer is a covering compound.
In accordance with an added feature of the invention, the covering compound has a thickness; and the flip-chip bumps are embodied as stud bumps made of a ductile material that has been compressed to have a thickness equal to the thickness of the covering compound by an injection mold that has injected the covering compound.
In accordance with an additional feature of the invention, the ductile material contains gold.
With the foregoing and other objects in view there is also provided, in accordance with the invention, a smart card module that includes: a connection lead frame forming a connection plane, the connection lead frame having contact areas; and a chip element placed onto the connection lead frame. The chip element includes a semiconductor chip electrically conductively contact-connected to the connection plane in which contact areas are formed. The semiconductor chip has sides. The semiconductor chip has contact-connection points. The chip element includes an electrically insulating protective layer located on at least one of the sides of the semiconductor chip. The electrically insulating protective layer has a surface that is remote from the semiconductor chip. The chip element includes pads formed on the surface of the electrically insulating protective layer that is remote from the semiconductor chip. The chip element includes flip-chip bumps electrically conductively connecting the pads to the contact-connection points of the semiconductor chip. The semiconductor chip and the electrically insulating protective layer are configured such that the pads are first on the connection plane and such that the pads electrically conductively contact-connect the semiconductor chip to the contact areas. The electrically insulating protective layer is applied only around the semiconductor chip. The flip-chip bumps extend through the electrically insulating protective layer. Each one of the flip-chip bumps has an end that is remote from the semiconductor chip. The end of each one of the flip-chip bumps forms a pad lying approximately plane-parallel in the surface of the electrically insulating protective layer that is remote
Fischer Jürgen
Heinemann Erik
Püschner Frank
Lee Michael G.
Sanders Allyson
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