Methods related to fabrication of shielded radio-frequency module

Abstract

According to one exemplary embodiment, an overmolded package includes a component situated on a substrate. The overmolded package further includes an overmold situated over the component and the substrate. The overmolded package further includes a wirebond cage situated over the substrate and in the overmold, where the wirebond cage surrounds the component, and where the wirebond cage includes a number of wirebonds. The wirebond cage forms an EMI shield around the component. According to this exemplary embodiment, the overmolded package further includes a conductive layer situated on a top surface of the overmold and connected to the wirebond cage, where the conductive layer forms an EMI shield over the component.

What is claimed is: 
     
         1 . A method for fabricating a packaged radio-frequency (RF) module, the method comprising:
 providing a packaging substrate having a reference potential layer;   mounting an RF component over the packaging substrate;   forming a plurality of wirebonds on the packaging substrate such that each of the plurality of wirebonds includes a first end electrically connected to the reference potential layer and a second end above the first end, the plurality of wirebonds arranged in a pattern relative to the RF component to yield electromagnetic shielding with respect to the RF component;   encapsulating the RF component and the plurality of wirebonds to yield an overmold with an upper surface that exposes the second ends of the plurality of wirebonds; and   forming a conductive layer on the upper surface of the overmold such that the conductive layer is in electrical contact with the second ends of the plurality of wirebonds.   
     
     
         2 . The method of  claim 1  wherein the forming of the plurality of wirebonds results in the pattern having a segment that separate a region associated with the RF component and another region on the packaging substrate, such that the pattern provides the electromagnetic shielding between the region and the other region. 
     
     
         3 . The method of  claim 1  wherein forming of the plurality of wirebonds results in the pattern having a perimeter around the RF component, such that the pattern provides the electromagnetic shielding between a region within the perimeter and a region outside of the perimeter. 
     
     
         4 . The method of  claim 3  wherein the perimeter is substantially at or near the perimeter of the packaging substrate. 
     
     
         5 . The method of  claim 1  wherein the packaging substrate includes a laminate substrate or a ceramic substrate. 
     
     
         6 . The method of  claim 1  wherein the mounting of the RF component includes positioning the RF component directly on the packaging substrate. 
     
     
         7 . The method of  claim 1  wherein the RF component includes a semiconductor die having an RF circuitry. 
     
     
         8 . The method of  claim 1  wherein the RF component includes a passive device. 
     
     
         9 . The method of  claim 1  wherein the packaging substrate further includes a plurality of bond pads electrically connected to the reference potential layer, such that the first end of each of one or more of the plurality of wirebonds is attached to a corresponding bond pad. 
     
     
         10 . The method of  claim 9  wherein the forming of the plurality of wirebonds includes forming each wirebond to a corresponding bond pad. 
     
     
         11 . The method of  claim 9  wherein the forming of the plurality of wirebonds includes forming each wirebond so that the wirebond extends generally upward from the corresponding bond pad. 
     
     
         12 . The method of  claim 11  wherein each wirebond is substantially straight. 
     
     
         13 . The method of  claim 1  wherein the forming of the plurality of wirebonds includes providing a spacing between an adjacent pair of wirebonds that is selected to provide the electromagnetic shielding for a particular frequency or range of frequencies. 
     
     
         14 . The method of  claim 13  wherein the spacing is substantially uniform among the adjacent pairs of wirebonds. 
     
     
         15 . The method of  claim 1  wherein forming the conductive layer includes spraying the conductive layer. 
     
     
         16 . The method of  claim 1  wherein the encapsulating includes applying a molding compound in a molding process. 
     
     
         17 . The method of  claim 16  wherein the encapsulating further includes removing at least some of the molding compound at or near the upper portion of the overmold to yield the upper surface. 
     
     
         18 . A method for shielding a radio-frequency (RF) module, the method comprising:
 providing a packaging substrate having a ground;   forming a plurality of wirebonds on the packaging substrate such that a portion of each wirebond is electrically connected to the ground, the plurality of wirebonds arranged in a pattern to yield electromagnetic shielding with respect to a region on the packaging substrate; and   implementing a conductive layer over the region and in electrical contact with another portion of each wirebond.