Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – Multiple housings
Reexamination Certificate
2002-08-12
2004-07-27
Lee, Eddie (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
Multiple housings
C257S685000, C257S683000
Reexamination Certificate
active
06768191
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an electronic component with stacked electronic elements and to methods of fabricating electronic components with stacked electronic elements.
Conventional techniques for stacking electronic elements are not based on FBGA (Fine Pitch Ball Grid Array) housings and there exists no satisfactory solution for stacking electronic elements with semiconductor chips in FBGA (Fine Pitch Ball Grid Array) housings. Additional problems result from the complications caused by the small raster dimension of the external contacts, and the two-dimensional external contact distribution of the FBGA style.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an electronic component with stacked electronic elements and methods for fabricating such electronic components which overcome the above-mentioned disadvantages of the heretofore-known components and methods of this general type and which allow the use of stacked elements with FBGA housings. The component should be inexpensive and easy to manufacture. Furthermore, the individual stacked elements should be replaceable at any time.
With the foregoing and other objects in view there is provided, in accordance with the invention, an electronic component, including:
electronic elements stacked on top of one another, the electronic elements including a topmost electronic element and a further electronic element disposed below the topmost electronic element;
each of the electronic elements having side edges and each of the electronic elements including a rewiring body with external contacts distributed thereon;
an isolating body;
an interconnect layer disposed on the isolating body, the interconnect layer having contact terminal pads;
the external contacts of the rewiring body of the topmost electronic element being connected to the contact terminal pads of the interconnect layer;
the interconnect layer extending over the side edges of one of the topmost electronic element and the further electronic element;
a further interconnect layer neighboring the interconnect layer, the interconnect layer and the further interconnect layer being detachably connected to one another; and
the further interconnect layer having contact terminal pads electrically connected to at least a respective further one of the electronic elements via the external contacts of the respective further one of the electronic elements.
In other words, the electronic component according to the invention includes stacked electronic elements, each of which includes a rewiring body with external contacts distributed on it. The external contacts of the topmost element are connected to contact terminal pads of a structured interconnect layer that is disposed on an isolating body. The interconnect layer extends over the underlying side edges of the top element or of another electronic element and is detachably connected to a subsequent interconnect layer of the stack. A subsequent interconnect layer is electrically connected by way of its contact terminal pads to at least one other electronic element by way of external contacts of this other electronic element. The advantage of this embodiment is that each element represents an individual element installed on the isolating body with an interconnect layer, which can be connected to the interconnect layers of similar elements at any time. The number of elements in an electronic component with stacked elements is thus unlimited. At the same time, the edge region of the isolating body with the structured interconnect layer can be bent in order to move it past the side edge of an element, thereby achieving a high elasticity and flexibility, which simplifies the stacking of the electronic elements. Furthermore, the stacked FBGA housing itself can be identical to the standard FBGA housing for non-stacked applications.
In another embodiment of the invention, the interconnect layer is disposed on a flexible plastic carrier which serves as the isolating body. Such a flexible plastic carrier has the advantage that it can be bent in its edge regions in a relatively stress-free fashion without stressing the individual stacked elements, and so the conductive track of the interconnect layer can extend over underlying side edges of electronic components in order to make contact with the next component, which is disposed in turn on such a flexible plastic carrier.
Another embodiment of the invention provides that the isolating body be a self-supporting flexible isolating film. Like a flexible plastic carrier, films of this type can, without giving rise to high stresses, be injected in the electronic element and bent around the side edges of an element so that contact can be made between the interconnect layer and the subsequent interconnect layers of the stack with corresponding additional electronic elements. If an electronic element should become defective, the flexible isolating film with its interconnect coating can be separated from the next element, i.e. the next isolating film, without a large technical expenditure, and a replacement element with a preformed interconnect layer can be inserted. To accomplish this, the interconnect layer on the flexible isolating film is bent around the side edges of an underlying element. Thus, after the bending, the external contact surfaces in the bent edge region of the interconnect layer are available on the bottom side, which can be placed directly on the topside of the next interconnect layer.
While the isolating body is preferably an isolating film, the rewiring body on the active topside of a semiconductor chip of an electronic element can be formed from a rewiring layer, a rewiring film or a rewiring plate.
In another embodiment of the invention, the rewiring body includes a bonding channel in its center, which includes contact surfaces of the active topside of the semiconductor chip. Bond connections are laid from the contact surfaces of the semiconductor chip to corresponding contact terminal pads in the rewiring plane of the rewiring body. From there, rewiring lines lead to the individual external contact surfaces of the rewiring body which bear the external contacts. These external contacts are distributed two-dimensionally on the rewiring plane of the rewiring body and correspond to corresponding contact terminal pads on the interconnect layer of the isolating body.
On their part, the interconnect layers of each electronic element include external contact surfaces in their edge regions, which are connectible to contact terminal pads of an additional interconnect layer in a stacked fashion. These external contact surfaces produce the connection to the next electronic element of the stack of electronic elements and are disposed on the bent edge regions of the interconnect layer. The top or outermost interconnect layer with its external contacts comes to the bottom side after the bending and can be connected to an underlying element by way of its interconnect layer.
In another embodiment of the invention, the packing density of the stack is increased in that isolating bodies with a double-sided coating of structured interconnect layers, for instance double-sided copper-laminated flexible conductive tracks, are utilized. After the bending of the edge regions, the bottom interconnect layer of the isolating body which is equipped on both sides lies on the top surface of the isolating body and is connected to the next interconnect layer of one of the next electronic elements by way of additional feedthroughs in the bent edge region.
In another embodiment of the invention, it is provided that the external contact surfaces include contact bumps or solder balls on the bent edge regions of the interconnect layers. These solder balls or contact bumps on the conductive track coating in the region of the bent edge of the isolating body can be connected to the corresponding contact terminal pads of the underlying interconnect layer of the next electronic element. Both the solder balls and the contact bumps of
Thomas Jochen
Wennemuth Ingo
Greenberg Laurence A.
Infineon - Technologies AG
Lee Eddie
Locher Ralph E.
Owens Douglas W.
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