Plastic electronic component package

Abstract

A plastic package for an image sensor or other electronic component which comprises a plastic body, preferably of LCP material, molded around a leadframe and defining a cavity in which the image sensor is to be disposed. A lid assembly is provided having a transparent glass lid retained in a plastic lid frame which is weldable or otherwise bondable to the plastic body of the package to enclose the image sensor mounted in the cavity. The leadframe is usually composed of copper or a copper alloy, or a ferrous alloy having a copper coating. An interfacial layer is formed on the surfaces of the leadframe at least in those portions which are in contact with the plastic body which serves to provide substantially improved adhesion between the leadframe and the plastic material to achieve a hermetic bond between the metal and plastic materials. The interfacial layer is composed of a cuprous oxide base layer formed on a surface of the leadframe, and a cupric oxide layer formed on the cuprous oxide layer. The cupric oxide outer layer has an acicular structure which provides an interlocking mechanism for adhesion to the plastic material molded thereto in forming the package.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 60 / 874,450, filed on Dec. 12, 2006, the disclosure of which is incorporated by reference herein.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]N / ABACKGROUND OF THE INVENTION[0003]Image sensors such as those used in digital cameras and other optical or image sensing equipment are conventionally housed in a ceramic package. The ceramic package includes a ceramic frame which is epoxy bonded to a glass lid or cover. The ceramic package is expensive and not readily adapted to manufacture in strip form or other multiple unit form, as is widely employed in the semiconductor packaging industry. In addition, the use of epoxy as a bonding agent presents several problems such as moisture penetration through the epoxy bond, outgassing of the epoxy which can contaminate the semiconductor device, and air leakage which limits the ...

AI Technical Summary

Benefits of technology

[0007]The image sensor package according to the present invention eliminates the need for ceramic components and employs a plastic material which preferably is a high temperature liquid crystal polymer (LCP) material. The package is useful not only for image sensors but also for other light sensing or light emitting semiconductor or other devices or components. A package in accordance with the invention can also be used to contain non-optical devices or components.

[0008]The image sensor package comprises a plastic body or frame, preferably of LCP material, molded around a metal leadframe and defining a cavity in which the image sensor is to be disposed. The leadframe has a central portion in the cavity on which the image sensor is mounted, and a plurality of leads which are connectable to contact areas of the sensor. A lid assembly is provided having a transparent glass lid retained in a lid frame which is also made of plastic, preferably LCP material. The lid frame is weldable or otherwise bondable to the plastic frame of the package to enclose the image sensor mounted in the cavity. The leadframe is usually composed of copper or a copper alloy, or a ferrous alloy having a copper coating. An interfacial layer is formed on the surfaces of the leadframe at least in those portions which are in contact with the plastic frame. This interfacial layer serves to provide substantially improved adhesion between the leadframe and the plastic material and to achieve a hermetic bond between the metal and plastic materials. The interfacial layer is composed of a cuprous oxide base layer formed on a surface of the leadframe, and a cupric oxide layer formed on the cuprous oxide layer. The cupric oxide outer layer has an acicular structure which provides an interlocking mechanism for adhesion to the plastic material molded thereto in forming the package.

Problems solved by technology

The ceramic package is expensive and not readily adapted to manufacture in strip form or other multiple unit form, as is widely employed in the semiconductor packaging industry.

In addition, the use of epoxy as a bonding agent presents several problems such as moisture penetration through the epoxy bond, outgassing of the epoxy which can contaminate the semiconductor device, and air leakage which limits the ability to hermetically seal the ceramic package.

Further, it is difficult to accurately align the glass cover to the ceramic frame so that the glass cover is parallel to the image sensor surface.

This alignment difficulty is caused by an inability to control the thickness of an epoxy bead which is commonly employed to seal the glass lid to the ceramic frame.

The requirement for UV curable adhesive materials limits the range of available epoxies which can be employed in the conventional ceramic package, since most epoxy adhesives are curable at elevated temperatures.

Moisture or corrosive gases on or near a semiconductor device can cause corrosion of the metallic traces on the semiconductor device, and can lead to failure.

These materials have such low permeabilities that moisture and fluids typically are impeded by these materials, and cause a condensation on the semiconductor device or contamination by corrosive gasses.

Images