Patent Application
20090179290
Embodiments herein relate to the field of integrated circuit packaging, and more specifically to integrated circuit imager packaging.
As the final step in the fabrication of a semiconductor integrated circuit, an integrated circuit is placed in packaging. The packaging serves to protect the integrated circuit from the environment and to provide a means for electrically connecting the integrated circuit to external components. As portable electronic devices have become smaller and more sophisticated, the challenge of minimizing the space used by integrated circuits and their respective packaging has continued to increase.
In conventional integrated circuit packaging techniques, the integrated circuits are packaged in a fully encapsulated manner, in which molding is used to fully enclose the integrated circuit for protection. However, if the integrated circuit is to be used as an imager device, light must be able to pass to the imager's photodetection area. Therefore, fully encapsulated packaging is not suitable for use with imager integrated circuits.
a is a cut-away side view of a leadless imager device packaging structure at a stage of manufacture in accordance with an embodiment described herein.
b is a top-down view of the leadless imager device packaging structure at the stage of manufacture shown in
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments described herein. These embodiments are described in sufficient detail to enable those skilled in the art to practice them, and it is to be understood that other embodiments may be utilized, and that structural, logical and electrical changes may be made.
One embodiment described herein provides a method of fabricating an imager device packaging structure using half encapsulation technology by which an integrated circuit is partially encapsulated by encapsulation material and further encapsulated by a transparent plate.
The integrated circuit 110 is mounted inside a cavity 130 of the package formed by a first encapsulant 116a, a second encapsulant 116b, and a transparent plate 118. The transparent plate 118 is formed of a transparent material, for example, glass, such as borosilicate glass, or transparent polymer, such as polycarbonate. The transparent plate 118 is arranged such that light may enter the leadless imager device packaging structure 100 through an opening 126 in the first encapsulant 116a and impinge upon the pixel array. The transparent plate 118 is coupled to the first encapsulant 116a by a sealant 120. A leadframe 122 is arranged in first encapsulant 116a. The leadframe 122 includes first conductor traces 122a to be electrically coupled to the integrated circuit 110 and second conductor traces 122b to be electrically coupled to an external device. The second conductor traces 122b have a flat portion 134 over a flat portion 136 of the first encapsulant 116a.
The first conductor traces 122a of the leadframe 122 may be coupled to the integrated circuit 110 by interconnect materials such as bumps 124, which may be formed of an electrically conductive material such as solder, and pads 132, which are part of the integrated circuit 110 and which may be formed of electrically conducting materials such as gold, copper, or aluminum. The integrated circuit 110 is bonded to the first conductive traces 122a by the solder bumps 124. The first conductor traces 122a of the leadframe 122, the integrated circuit 110, pads 132, and bumps 124 may also be further held together using one or more adhesives 128, such as Anisotropic Conductive Film (ACF), Anisotropic Conductive Paste (ACP), Non-conductive Film (NCF), and Non-conductive Paste (NCP).
An example method of making a leadless imager device packaging structure 100 in accordance with an embodiment is now described.
After the leadframe 122 is attached to the first encapsulant 116a, a transparent plate 118 is attached to a lower flat surface of the first encapsulant 116a as shown in
Next, as shown in
One or more adhesives 128, such as Anisotropic Conductive Film (ACF), Anisotropic Conductive Paste (ACP), Non-conductive Film (NCF), and Non-conductive Paste (NCP), may be used to couple the integrated circuit 110 to the leadframe 122 and first encapsulant 116a. If ACF or NCF is used, the ACF and NCF may be pre-cut and attached to the first conductor traces 122a. If ACP, NCP, or a type of underfill is used, the ACP or NCP or underfill may be dispensed onto the first conductor traces 122a.
After mounting the integrated circuit 110, the integrated circuit may be encapsulated, for example by dispensing or by a Boschman processes, with a second encapsulant 116b, which may be the same or different material than the first encapsulant 116a used to form the cavity 130.
The integrated circuit 110 is thus partially encapsulated by the first encapsulant 116a and the second encapsulant 116b and is further encapsulated by the transparent plate 118. The integrated circuit 110 will therefore be protected within the package while still allowing light to reach the pixel array 114. Furthermore, the half-encapsulated packaging structure allows the transparent plate 118 to be located close to the pixel array, which may provide better optical performance in an imager device. In one embodiment, the leadless imager device packaging structure 100 may be fabricated using existing leadframe molding equipment and known cost effective molding materials.
The above description and drawings illustrate embodiments, which achieve the objects, features, and advantages described herein. However, it is not intended that the invention be strictly limited to the described and illustrated embodiments. For example, although embodiments have been described as being useful for producing an imager device, it should be appreciated that embodiments could be used to mount other types of integrated circuits as well, including, but not limited to, integrated circuits requiring an input light transmission. Furthermore, although the method embodiments have been described with regard to one package, it should be appreciated that multiple packages may be formed by this process at one time.
