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.

1 . An image sensor package comprising:
 a plastic frame molded around a metal leadframe and defining a cavity;   the leadframe having a central portion in the cavity and a plurality of leads;   the central portion of the leadframe in the cavity adapted to have an image sensor mounted thereon and connected to the plurality of leads;   a lid assembly having a transparent lid retained in a plastic lid frame; and   the lid frame being weldable to the plastic frame to enclose an image sensor mounted in the cavity.   
     
     
         2 . The image sensor package of  claim 1  wherein the plastic frame and the lid frame are each a high temperature thermoplastic material. 
     
     
         3 . The image sensor package of  claim 2  wherein the plastic frame and the lid frame are each a high temperature LCP material. 
     
     
         4 . The image sensor package of  claim 2  wherein the LCP material has a melting temperature greater than about 300° C. 
     
     
         5 . The image sensor package of  claim 2  wherein the LCP material has a melting temperature greater than about 200° C. 
     
     
         6 . The image sensor package of  claim 2  wherein the LCP material contains filler particles to provide a CTE compatible with that of the metal lead frame. 
     
     
         7 . The image sensor package of  claim 6  wherein the CTE of the LCP material is in the range of about 6-25 ppm/° C. 
     
     
         8 . The image sensor package of  claim 6  wherein the filler particles are of nano size. 
     
     
         9 . The image sensor package of  claim 6  wherein the filler particles are in the range of about 10-17% by weight. 
     
     
         10 . The image sensor package of  claim 2  wherein the leadframe is copper. 
     
     
         11 . The image sensor package of  claim 2  wherein the leadframe is a copper alloy. 
     
     
         12 . The image sensor package of  claim 2  wherein the leadframe is a ferrous metal having copper surfaces. 
     
     
         13 . A method of fabricating an electronic component package, the method comprising the steps of:
 providing a metal leadframe;   providing on at least a portion of the surfaces of the metal leadframe an interfacial layer of oxide material;   molding a plastic frame around the portion of the metal leadframe having the interfacial layer, the frame defining a cavity;   the leadframe having a central portion in the cavity and a plurality of leads;   mounting an electronic component on the central portion of the leadframe in the cavity and connecting the component to the plurality of leads;   providing a lid assembly having a transparent lid bonded to a plastic lid frame; and   welding the lid frame to the plastic frame to enclose the component.   
     
     
         14 . A hermetically sealable electronic component package comprising:
 a high temperature plastic frame molded to a metal leadframe and defining a cavity;   the leadframe having a central portion in the cavity and a plurality of leads;   the central portion of the leadframe adapted to have an electronic component mounted thereon and connected to the plurality of leads;   a lid assembly having a lid of high temperature plastic retained in a lid frame of high temperature plastic; and   the lid frame being weldable to the plastic frame to enclose an electronic component mounted in the cavity.   
     
     
         15 . The package of  claim 14  wherein the metal leadframe has on the surfaces thereof which are molded to the plastic frame an interfacial layer of material effective to improve the adhesion of the high temperature plastic frame to the metal leadframe. 
     
     
         16 . The package of  claim 14  wherein the leadframe is composed of copper;
 and wherein an interfacial layer is formed on at least the surfaces of the leadframe in contact with the plastic frame, the interfacial layer composed of a cuprous oxide layer formed on the surface of the leadframe and a cupric oxide layer formed on the surface of the cuprous oxide layer.   
     
     
         17 . The package of  claim 15  wherein the interfacial layer has:
 a first layer formed on a surface of the metal leadframe; and   a second layer formed on a surface of the first layer, the second layer having a surface bonded to the high temperature plastic frame.   
     
     
         18 . The package of  claim 15  wherein the leadframe has a copper surface;
 the interfacial layer has a first layer of cuprous oxide formed on the copper surface of the leadframe; and   a layer of cupric oxide formed on a surface of the cuprous layer, the cupric layer having an acicular structure bonded to the high temperature plastic frame.   
     
     
         19 . For use in fabricating a hermetically sealed electronic package having a high temperature plastic frame molded to a copper leadframe and defining a cavity, a leadframe comprising:
 a first layer of cuprous oxide formed on the surfaces of the leadframe at least at the portions to be molded to the high temperature plastic frame; and   a second layer of cupric oxide formed on the first layer and having an acicular structure bondable to the high temperature plastic frame.   
     
     
         20 . A hermetic seal between a metal element and a plastic element comprising:
 an intermediate layer between the metal element and the plastic element, the intermediate layer having:   a layer of a first oxide formed on a surface of the metal element; and   a layer of a second oxide formed on the layer of a first oxide, the second oxide layer having an acicular structure bondable to the plastic element.   
     
     
         21 . The hermetic seal of  claim 20  wherein:
 the first oxide is an oxide of the metal material of the metal element; and   the second oxide is a different oxide form of the first oxide.   
     
     
         22 . The hermetic seal of  claim 21  wherein:
 the metal element has a copper surface at least in the area bondable to the plastic element;   the first oxide is cuprous oxide and the second oxide is cupric oxide.   
     
     
         23 . For use in a hermetically sealable plastic electronic component package having a plastic frame molded around a metal leadframe and defining a cavity in which an electronic component is mountable, a lid assembly comprising:
 a lid sized and configured to cover the cavity of the plastic frame of the package; and   a plastic lid frame bondable to the lid and weldable to the plastic frame of the package to enclose and hermetically seal the package cavity.   
     
     
         24 . A method of constructing a lid assembly having a transparent lid bonded to a plastic lid frame, the method comprising the steps of:
 sawing a transparent lid to a predetermined size;   injection molding a plastic lid; and   attaching the transparent lid to the plastic lid by thermal bonding.   
     
     
         25 . A method of constructing a lid assembly having a transparent lid bonded to a plastic lid frame, the method comprising the steps of:
 sawing transparent lid to a predetermined size; and   injection molding a plastic lid directly onto the transparent lid by overmolding.   
     
     
         26 . A method of thermally bonding a transparent lid to a plastic lid frame, the method comprising the steps of:
 heating the transparent lid in a fixture;   heating the plastic lid in a mating fixture;   mating the transparent lid and the plastic lid to a fixed displacement such that the material of the plastic lid contacts the transparent lid and locally melts to it; and   cooling the assembly in place.   
     
     
         27 . The method of  claim 13  wherein the step of welding the lid frame to the plastic frame comprises ultrasonic welding of the lid frame to the plastic frame;
 and wherein the ultrasonic welding is applied only to the perimeter of the lid frame.   
     
     
         28 . A method of fabricating an electronic component package, the method comprising the steps of:
 providing a metal leadframe;   providing on at least a portion of the surfaces of the metal leadframe an interfacial layer of oxide material;   molding a high temperature thermoplastic frame around the portion of the metal leadframe having the interfacial layer, the frame defining a cavity;   the leadframe having a central portion in the cavity for mounting an electronic component, and a plurality of leads connectable to the electronic component;   providing a lid assembly having a transparent lid bonded to a high temperature thermoplastic lid frame; and   welding the lid frame to the plastic frame to enclosed the component mounted in the cavity.   
     
     
         29 . The method of  claim 28  wherein the LCP material contains hydroquinine (HQ), teraphalic acid, isophalic acid, 2, 6 naphalene, dicarboxyclic acid, 4-hydrobenzoic acid (HBA), bisphenol or biphenol (BP), and hydroxynaphthoic acid;
 and filler particles of at least one of the group consisting of talc, glass fiber, milled glass and flake glass.   
     
     
         30 . The method of  claim 29  wherein the filler particles are in the range of 10-50% by weight. 
     
     
         31 . The method of  claim 30  wherein at least some of the filler particles have a particle size in the range of about 50-350 microns. 
     
     
         32 . The method of  claim 28  wherein the step of providing an interfacial layer includes providing a first oxide on at least a portion of the surfaces of the metal leadframe, and providing a second oxide on the first oxide. 
     
     
         33 . The method of  claim 32  wherein the step of providing the interfacial layer includes providing the interfacial layer on the entire surface of the leadframe;
 and further including the step of removing the exposed portions of the interfacial layer from the leadframe after molding the high temperature thermoplastic frame.   
     
     
         34 . The method of  claim 28  wherein the metal leadframe is copper and wherein the interfacial layer is copper oxide material. 
     
     
         35 . The method of  claim 28  wherein the step of molding comprises injection molding the high temperature thermoplastic frame;
 wherein the step of providing a lid assembly comprises injection molding the lid frame and bonding the transparent lid thereto.   
     
     
         36 . The method of  claim 28  wherein the step of welding comprises ultrasonic welding the lid frame to the plastic frame.