Abstract:
Methods and systems for a molded cavity substrate Micro Electro Mechanical Systems (MEMS) package may comprise a MEMS electronic component, a base substrate comprising a first conductive through via, a molded ring coupled to the base substrate, and a lid substrate comprising dielectric material and a metal layer. The molded ring comprises a second conductive through via and a molded cavity, and the MEMS electronic component is located within the molded cavity. The base substrate may comprise a laminate substrate. The lid substrate may comprise a cavity port. A base assembly mounting adhesive may couple an inner surface of the lid to a principal surface of the molded ring. The dielectric material may comprise mold material. The molded ring may comprise mold compound adherent to an outer region of an inner surface of the base substrate with a central region of the base substrate exposed by the molded ring.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 13/272,096 filed on Oct. 12, 2011, which is hereby incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present application relates to the field of electronics, and more particularly, to methods of forming electronic component packages and related structures. 
     BACKGROUND 
     A Micro Electro Mechanical Systems (MEMS) package includes a MEMS sensor die, sometimes called a MEMS electronic component or transducer. As the MEMS sensor die receives external mechanical stimulus such as motion, sound waves or pneumatic pressure, the variations in the stimulus signals are converted to electrical signals. 
     The MEMS sensor die is located within a cavity of the MEMS package. However, forming the cavity of the MEMS package is relatively complex thus increasing the fabrication cost of the MEMS package. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a molded cavity substrate Micro Electro Mechanical Systems (MEMS) package in accordance with one embodiment; 
         FIG. 2  is a bottom plan view taken from the direction of arrow II in  FIG. 1  of a base assembly of the molded cavity substrate MEMS package in accordance with one embodiment; 
         FIG. 3  is a top plan view taken from the direction of arrow III in  FIG. 1  of a molded cavity substrate of the molded cavity substrate MEMS package in accordance with one embodiment; 
         FIG. 4  is a top plan view of a molded cavity substrate array of molded cavity substrates in accordance with one embodiment; and 
         FIGS. 5, 6, 7  are cross-sectional views of molded cavity substrate MEMS packages in accordance with various embodiments. 
     
    
    
     In the following description, the same or similar elements are labeled with the same or similar reference numbers. 
     DETAILED DESCRIPTION 
     As an overview and in accordance with one embodiment, referring to  FIG. 1 , a molded ring  320  includes a molded cavity  342  of a molded cavity substrate MEMS package  100 . Molded ring  320  is formed by molding a dielectric material directly upon a substrate  302 . As molding is a relatively simple and low cost process, molded ring  320  and thus molded cavity  342  are formed at a minimal cost. This, in turn, minimizes the cost of molded cavity substrate MEMS package  100 . 
     Now in more detail,  FIG. 1  is a cross-sectional view of a molded cavity substrate Micro Electro Mechanical Systems (MEMS) package  100  in accordance with one embodiment. Molded cavity substrate MEMS package  100  includes a base assembly  102  and a molded cavity substrate  104  joined together by a base assembly mounting adhesive  106 . 
       FIG. 2  is a bottom plan view taken from the direction of arrow II in  FIG. 1  of base assembly  102  of molded cavity substrate MEMS package  100  in accordance with one embodiment. Referring now to  FIGS. 1 and 2  together, base assembly  102  includes a substrate  202 . 
     Substrate  202  includes a dielectric material such as laminate, ceramic, printed circuit board material, or other dielectric material. Substrate  202  includes an inner surface  204 , an opposite outer surface  206 , and sides  208 . 
     Substrate  202  further includes inner, e.g., first, traces  210  and ground terminals  212  formed at inner surface  204 . Although two inner traces  210  and four ground terminals  212  are illustrated in  FIG. 2 , in light of this disclosure, those of skill in the art will understand that molded cavity substrate MEMS package  100  is formed with one or more inner traces  210  and one or more ground terminals  212  depending upon the particular input/output (I/O) required. 
     Further, substrate  202  includes an electrically conductive ground plane  214  at outer surface  206 . Ground terminals  212  are electrically connected to ground plane  214  by electrically conductive vias  216  extending through substrate  202  between inner surface  204  and outer surface  206 . 
     Substrate  202  can further include an inner, e.g., first, solder mask at inner surface  204  that protects first portions of inner traces  210  while exposing second portions, e.g., bond fingers  218  and MEMS terminals  220 , of inner traces  210  and exposing ground terminals  212 . 
     Although a particular electrically conductive pathway is described above, other electrically conductive pathways can be formed. For example, contact metallizations can be formed between the various electrical conductors. 
     Further, instead of straight though vias  216 , in one embodiment, substrate  202  is a multilayer substrate and a plurality of vias and/or internal traces form the electrical interconnection between ground terminals  212  and ground plane  214 . 
     Base assembly  102  further includes a MEMS electronic component  222 . MEMS electronic component  222  is a conventional MEMS electronic component, sometimes called a MEMS chip. Accordingly, the features and functions of MEMS electronic component  222  are well known to those of skill in the art. Thus, only a general description of various features and functions of MEMS electronic component  222  are set forth below. Generally, MEMS electronic component  222  includes a mechanical element(s) that produce an electrical signal(s) from external excitations. 
     For purposes of illustration, MEMS electronic component  222  will be illustrated and described as an acoustical microphone, e.g., a silicon microphone, although can be another type of MEMS electronic component such as a pressure sensor, an optical sensor, a gyroscope, an accelerometer, a stress sensitive non-sensor device, or other MEMS electronic component as discussed further below. 
     In accordance with this embodiment, MEMS electronic component  222  includes a frontside surface  224  and an opposite backside surface  226 . Backside surface  226  is mounted to inner surface  204  of substrate  202  with an adhesive  228 . 
     MEMS electronic component  222  further includes a moveable compliant diaphragm  230  and one or more bond pads  232  formed at frontside surface  224 . MEMS electronic component  222  further includes a rigid perforated backplate  234  at backside surface  226 . 
     MEMS electronic component  222  further includes an aperture  236  extending through MEMS electronic component  222  and between frontside surface  224  and backside surface  226 . More particularly, aperture  236  extends between and separates diaphragm  230  and backplate  234  such that diaphragm  230  and backplate  234  form a capacitor. 
     As described further below, during operation, sound waves (or pressure waves in other embodiments) move diaphragm  230  thus causing changes in the capacitance between diaphragm  230  and backplate  234 . An electrical signal corresponding to the capacitance variations is output on bond pads  232 . 
     Base assembly  102  further includes a converter electronic component  238 . Converter electronic component  238  is a conventional converter electronic component, sometimes called an Application Specific Integrated Circuit (ASIC) chip. Accordingly, the features and functions of converter electronic component  238  are well known to those of skill in the art. Thus, only a general description of various features and functions of converter electronic component  238  are set forth below. Generally, converter electronic component  238  converts the signals(s) from MEMS electronic component  222  as required for the particular application. 
     Converter electronic component  238  includes a frontside, e.g., active, surface  240  and an opposite backside, e.g., inactive, surface  242 . Backside surface  242  is mounted to inner surface  204  of substrate  202  with an adhesive  244 . Frontside surface  240  includes bond pads  246 . 
     Bond pads  246  of converter electronic component  238  are electrically connected to respective bond fingers  218  of inner traces  210  with electrically conductive bond wires  248 . 
     In accordance with another embodiment, converter electronic component  238  is mounted in a flip chip configuration. Illustratively, flip chip bumps, e.g., solder, forms the physical and electrical interconnection between bond pads  246  of converter electronic component  238  and bond fingers  218  of inner traces  210 . Optionally, an underfill is applied between converter electronic component  238  and substrate  202 . 
     In accordance with yet another embodiment, molded cavity substrate MEMS package  100  is formed without converter electronic component  238 . Illustratively, the functionality of converter electronic component  238  is incorporated into MEMS electronic component  222 . Accordingly, a separate converter electronic component  238  is unnecessary and not provided. 
     Bond pads  232  of MEMS electronic component  222  are electrically connected to respective bond fingers  218  of inner traces  210  with electrically conductive bond wires  250 . Optionally, one or more of bond pads  232  of MEMS electronic component  222  are electrically connected to respective one or more bond pads  246  of converter electronic component  238  with bond wires  250 . 
     Accordingly, bond pads  232  of MEMS electronic component  222  are electrically connected to respective bond fingers  218  of inner traces  210 , to respective bond pads  246  of converter electronic component  238 , or to both respective bond fingers  218  of inner traces  210  and respective bond pads  246  of converter electronic component  238 . Generally, bond pads  232  of MEMS electronic component  222  are electrically connected to respective bond fingers  218  of inner traces  210  either directly by bond wires  250  or indirectly through converter electronic component  238 . 
     Substrate  202  further includes a base assembly port  252 . Base assembly port  252  is an aperture, sometimes called an opening or hole, extending through substrate  202  between outer surface  206  and inner surface  204  including through ground plane  214 . Base assembly port  252  extends through substrate  202  to backplate  234  and generally to aperture  236  of MEMS electronic component  222 . 
     Base assembly port  252  is in fluid communication with aperture  236  of MEMS electronic component  222  and thus with diaphragm  230  of MEMS electronic component  222 . As used herein, regions are in fluid communication when they are directly connected to one another without an intervening structure such that fluid, e.g., air, and sound can freely move from one region to the other. 
     Accordingly, during use, sound travels through base assembly port  252 , passes through backplate  234 , through aperture  236  and moves diaphragm  230 . As described above, the motion of diaphragm  230  from the sound is converted into an electrical signal that is output on bond pads  232 . 
     Molded cavity substrate MEMS package  100  further includes molded cavity substrate  104 .  FIG. 3  is a top plan view taken from the direction of arrow III in  FIG. 1  of molded cavity substrate  104  of molded cavity substrate MEMS package  100  in accordance with one embodiment. 
     Referring now to  FIGS. 1, 2, and 3  together, molded cavity substrate  104  includes a substrate  302 . Substrate  302  of molded cavity substrate  104  is sometimes called a first substrate and substrate  202  of base assembly  102  is sometimes called a second substrate. 
     Substrate  302  includes a dielectric material such as laminate, ceramic, printed circuit board material, or other dielectric material. Substrate  302  includes an inner surface  304 , an opposite outer surface  306 , and sides  308 . 
     Substrate  302  further includes inner terminals  310  formed at inner surface  304 . Further, substrate  302  includes outer traces  312  at outer surface  306 . Inner terminals  310  are electrically connected to outer traces  312  by electrically conductive vias  314  extending through substrate  302  between inner surface  304  and outer surface  306 . 
     Outer traces  312  include lands  316 . In one embodiment, lands  316  are distributed in an array thus forming a Land Grid Array (LGA). Alternatively, interconnection balls  318 , e.g., solder balls, are formed on lands  316  thus forming a Ball Grid Array (BGA). Interconnection balls  318  or, alternatively, lands  316  are used to electrically connect molded cavity substrate MEMS package  100  to a larger substrate such as a printed circuit mother board. 
     Substrate  302  can further include solder masks at inner and/or outer surfaces  304 ,  306 , e.g., that protect first portions of outer traces  312  while exposing second portions, e.g., lands  316 , of outer traces  312  and exposing inner terminals  310 . 
     Although a particular electrically conductive pathway is described above, other electrically conductive pathways can be formed. For example, contact metallizations can be formed between the various electrical conductors. 
     Further, instead of straight though vias  314 , in one embodiment, substrate  302  is a multilayer substrate and a plurality of vias and/or internal traces form the electrical interconnection between inner terminals  310  and outer traces  312 . 
     Molded cavity substrate  104  further includes a molded ring  320 . Molded ring  320  is a cured liquid encapsulant, molding compound, or other dielectric material. In one embodiment, molded ring  320  is formed by molding a dielectric material on inner surface  304  of substrate  302 . 
     Molded ring  320  includes a substrate surface  322 , a principal surface  324 , inner sidewalls  326 , and outer sidewalls  328 . Substrate surface  322  is parallel to principal surface  324 . Inner and outer sidewalls  326 ,  328  extend perpendicularly between substrate surface  322  and principal surface  324 . 
     Although the terms parallel, perpendicular, and similar terms are used herein, it is to be understood that the described features may not be exactly parallel and perpendicular, but only substantially parallel and perpendicular to within accepted manufacturing tolerances. 
     Substrate surface  322  directly adheres to inner surface  304  of substrate  302 . Illustratively, molded ring  320  is molded directly to inner surface  304  of substrate  302  such that substrate surface  322  is parallel to and coplanar with inner surface  304  of substrate  302 . In one embodiment, substrate surface  322  is identical in shape to principal surface  324  as described in detail below. 
     More particularly, substrate surface  322  directly adheres to an outer peripheral region  330  of inner surface  304  of substrate  302  while exposing a central region  332  of inner surface  304  of substrate  302 . 
     Principal surface  324  is an annular surface in accordance with this embodiment. Principal surface  324  is defined by an inner edge  334  and an outer edge  336  of principal surface  324 . In one embodiment, inner edge  334  and outer edge  336  are rectangular in the top plan view, i.e., in the view of  FIG. 3 . 
     However, in other embodiments, inner edge  334  and/or outer edge  336  can have shapes other than rectangular. For example, to increase the surface area of principal surface  324  to allow more through vias  338  to be formed in molded ring  320 , inner edge  334  can have one or more rounded corners  340  as indicated by the dashed line in  FIG. 3 . 
     Molded ring  320  includes a molded cavity  342 . More particularly, the exposed central region  332  of inner surface  304  of substrate  302  and inner sidewalls  326  define molded cavity  342  of molded cavity substrate  104 . 
     As set forth above, molded ring  320  is formed by molding a dielectric material directly upon substrate  302 . As molding is a relatively simple and low cost process, molded ring  320  and thus molded cavity  342  are formed at a minimal cost. This, in turn, minimizes the cost of molded cavity substrate MEMS package  100 . 
     Molded cavity substrate  104  further includes electrically conductive through vias  338 . Through vias  338  extend through molded ring  320  between substrate surface  322  and principal surface  324 . More particularly, through vias  338  are formed on inner terminals  310  and extend perpendicularly upward from inner terminals  310  through molded ring  320 . 
     In one embodiment, the exposed outer via surfaces  344  of through vias  338  are recessed below principal surface  324 . Illustratively, through vias  338  are formed of pre-attached solder balls on inner terminals  310 . The pre-attached solder balls are overmolded by molded ring  320  to completely cover the pre-attached solder balls. Via apertures  346  are formed in principal surface  324 , e.g., by laser-ablation, to expose the pre-attached solder balls, which thus form through vias  338 . 
     However, in other embodiments, through vias  338  are formed using other through via formation techniques. For example, via apertures are formed in molded ring  320  to expose inner terminals  310 . These via apertures are filled with an electrically conductive material, e.g., solder, electrically conductive adhesive, or other electrically conductive material, to form through vias  338 . In various embodiments, exposed outer via surfaces  344  of through vias  338  are recessed below or protrude above principal surface  324 . 
     In yet another embodiment, exposed outer via surfaces  344  of through vias  338  are parallel to and coplanar with principal surface  324 . Illustratively, through vias  338  are formed of pre-attached solder balls on inner terminals  310 . The pre-attached solder balls are overmolded by molded ring  320  to completely cover the pre-attached solder balls. Molded ring  320  may be ground down from principal surface  324  to expose the pre-attached solder balls, which thus form through vias  338  having exposed outer via surfaces  344  parallel to and coplanar with principal surface  324 . 
     In accordance with the illustrated embodiment, through vias  338  include one or more ground vias  348  and one or more MEMS vias  350 , sometimes called MEMS signal vias  350 . More particularly, ground vias  348  and MEMS vias  350  are identical in structure, i.e., are first and second sets of through vias  338 . However ground vias  348  are electrically connected to ground plane  214  of base assembly  102  as discussed further below. In contrast, MEMS vias  350  are connected to MEMS electronic component  222  and/or to converter electronic component  238  of base assembly  102 . 
     As illustrated in  FIG. 1 , inner surface  204  of substrate  202  of base assembly  102  is mounted to principal surface  324  of molded ring  320  of molded cavity substrate  104  such that ground vias  348  are aligned with ground terminals  212  and MEMS vias  350  are aligned with MEMS terminals  220  of inner traces  210 . 
     As illustrated in  FIGS. 1 and 2 , ground vias  348  are electrically connected to ground terminals  212  by base assembly mounting adhesive  106 . In one embodiment, base assembly mounting adhesive  106  is electrically conductive adhesive, although can be other electrically conductive materials such as solder or paste. 
     In one embodiment, base assembly mounting adhesive  106  electrically connects ground vias  348  to ground terminals  212  in a many to many relationship. More particularly, all of ground vias  348  are electrically connected to all of ground terminals  212  by base assembly mounting adhesive  106 . For example, base assembly mounting adhesive  106  seals the entire outer periphery  254  of inner surface  204  to the entire principal surface  324  of molded ring  320  while at the same time electrically connecting ground vias  348  to ground terminals  212 . 
     During operation, the respective interconnection balls  318  connected to ground plane  214  are electrically connected to a reference voltage source, e.g., ground. More particularly, the reference voltage source is coupled from the respective interconnection balls  318  through the respective lands  316 , outer traces  312 , vias  314 , inner terminals  310 , ground vias  348 , base assembly mounting adhesive  106 , ground terminals  212 , vias  216 , and to ground plane  214 . 
     Ground plane  214  is formed of an electrically conductive material to provide Radio Frequency (RF) shielding or more generally to provide shielding from ElectroMagnetic Interference (EMI). For example, when MEMS electronic component  222  is a silicon (Si) microphone, ground plane  214  shields MEMS electronic component  222  from EMI. 
     However, in another embodiment where shielding is unnecessary, molded cavity substrate MEMS package  100  is formed without ground plane  214  and without the respective interconnection balls  318 , lands  316 , outer traces  312 , vias  314 , inner terminals  310 , ground vias  348 , base assembly mounting adhesive  106 , ground terminals  212 , and vias  216 . For example, MEMS electronic component  222  is an optical MEMS or pressure sensor that does not require shielding and so ground plane  214  and the associated conductors are not formed. In accordance with this embodiment, base assembly mounting adhesive  106  can be either a dielectric or conductive material. 
     In another embodiment, MEMS electronic component  222 , sometimes referred to as an electronic component  222 , is a MEMS or non-MEMS sensor that benefits from the low stress cavity environment provided by embodiments as described herein. 
     Referring again to the embodiment illustrated in  FIGS. 1, 2, and 3 , base assembly mounting adhesive  106  and thus ground plane  214  is electrically isolated from inner traces  210 . More particularly, base assembly mounting adhesive  106  is patterned around MEMS terminals  220  to avoid contact and electrical interconnection (shorting) therewith. 
     MEMS vias  350  are electrically connected to MEMS terminals  220  by MEMS via interconnect material  256 . In one embodiment, MEMS via interconnect material  256  is electrically conductive adhesive, although can be other electrically conductive materials such as solder. 
     In one embodiment, MEMS via interconnect material  256  electrically connects MEMS vias  350  to MEMS terminals  220  in a one to one relationship. More particularly, each MEMS via  350  is electrically connected to a respective MEMS terminal  220  by a respective MEMS via interconnect material  256 . 
     During operation, signals are propagated to/from the respective interconnection balls  318  and to bond pads  232  of MEMS electronic component  222  and/or to bond pads  246  of converter electronic component  238 . More particularly, signals are propagated to/from the respective interconnection balls  318  through the respective lands  316 , outer traces  312 , vias  314 , inner terminals  310 , MEMS vias  350 , MEMS via interconnection materials  256 , MEMS terminals  220 , inner traces  210 , bond fingers  218 , bond wires  248  and/or bond wires  250 , and to bond pads  232  of MEMS electronic component  222  and/or to bond pads  246  of converter electronic component  238 . 
     As set forth above, base assembly mounting adhesive  106  seals the entire outer periphery  254  of inner surface  204  to the entire principal surface  324  of molded ring  320 . Accordingly, molded cavity  342  of molded cavity substrate  104  is sealed by base assembly  102  and base assembly mounting adhesive  106 . 
     MEMS electronic component  222  and converter electronic component  238  are located within molded cavity  342 . As set forth above, in one embodiment, base assembly port  252  extends through substrate  202  to backplate  234  and generally to aperture  236  of MEMS electronic component  222 . In accordance with this embodiment, molded cavity  342  defines a back volume. 
     In another embodiment, instead of providing base assembly port  252 , a molded cavity substrate port  352  is formed in molded cavity substrate  104 . More particularly, molded cavity substrate port  352  is an aperture, sometimes called an opening or hole, extending through substrate  302  between outer surface  306  and inner surface  304 . Molded cavity substrate port  352  extends through substrate  302  to molded cavity  342 . 
     Molded cavity substrate port  352  is in fluid communication with molded cavity  342  and thus with diaphragm  230  of MEMS electronic component  222 . In accordance with this embodiment, aperture  236  of MEMS electronic component  222  defines a back volume. 
     In accordance with another embodiment, molded cavity substrate MEMS package  100  includes both base assembly port  252  and molded cavity substrate port  352 . For example, MEMS electronic component  222  is a differential or gauge pressure sensor that senses the difference in pressure at base assembly port  252  and molded cavity substrate port  352 . 
     In accordance with another embodiment, molded cavity substrate MEMS package  100  does not include either base assembly port  252  or molded cavity substrate port  352 . For example, MEMS electronic component  222  does not need to be in fluid communication with the ambient environment. For example MEMS electronic component  222  is a gyroscope (gyro), accelerometer, a stress sensitive device, and/or combinations thereof, e.g., includes single or multiple MEMS dies sealed within molded cavity  342 . 
     As illustrated in  FIG. 1 , sides  208  of substrate  202 , outer sidewalls  328  of molded ring  320 , and sides  308  of substrate  302  are parallel to and coplanar with one another. Illustratively, molded cavity substrate MEMS package  100  is formed simultaneously with a plurality of packages in an array or strip. The array or strip is singulated resulting in sides  208 , outer sidewalls  328 , and sides  308  being parallel to and coplanar with one another. 
       FIG. 4  is a top plan view of a molded cavity substrate array  400  of molded cavity substrates  104  in accordance with one embodiment. Referring now to  FIGS. 1 and 4  together, molded cavity substrates  104  are integrally connected together within molded cavity substrate array  400 . Molded cavity substrates  104  are delineated from one another by singulation streets  402 . 
     In one embodiment, to form molded cavity substrate array  400 , a substrate array  404  of substrates  302  integrally connected together is provided. Pre-attached solder balls are formed on inner terminals  310  of substrates  302 . The pre-attached solder balls are overmolded by a molded ring array  406  of molded rings  320  to completely cover the pre-attached solder balls. Via apertures  346  are formed in molded rings  320 , e.g., by laser-ablation, to expose the pre-attached solder balls, which thus form through vias  338 . 
     However, in other embodiments, through vias  338  are formed using other through via formation techniques. For example, via apertures are formed in molded rings  320  to expose inner terminals  310  of substrates  302 . The via apertures are filled with an electrically conductive material, e.g., solder, electrically conductive adhesive, or other electrically conductive material, to form through vias  338 . 
     In yet another embodiment, pre-attached solder balls are formed on inner terminals  310  of substrates  302 . The pre-attached solder balls are overmolded by molded ring array  406  of molded rings  320  to completely cover the pre-attached solder balls. Molded ring array  406  including molded rings  320  are ground down from principal surfaces  324  to expose the pre-attached solder balls, which thus form through vias  338 . 
     After fabrication of molded cavity substrate array  400  as discussed above, a base assembly  102  is attached to each molded ring  320  in a manner similar to that described above. In one embodiment, a base assembly array including a plurality of base assemblies  102  is attached to molded cavity substrate array  400 . The resulting assembly is then singulated along singulation streets  402  resulting in a plurality of individual molded cavity substrate MEMS packages  100 . 
     In another embodiment, individual base assemblies  102  are mounted one at a time to each molded ring  320  of molded cavity substrate  400 . The resulting assembly is then singulated along singulation streets  402  resulting in a plurality of individual molded cavity substrate MEMS packages  100 . 
     In yet another embodiment, molded cavity substrate MEMS packages  100  are fabricated individually. For example, molded cavity substrate  400  is singulated to form a plurality of individual molded cavity substrates  104 . Alternatively, molded cavity substrates  104  are formed individually, e.g., by molding a molded ring  320  upon an individual substrate  302 . In either embodiment, a base assembly  102  is mounted individually to an individual molded cavity substrate  104 . 
       FIG. 5  is a cross-sectional view of a molded cavity substrate MEMS package  500  in accordance with one embodiment. Molded cavity substrate MEMS package  500  of  FIG. 5  is similar to molded cavity substrate MEMS package  100  of  FIG. 1  and only the significant differences are described below. 
     Referring now to  FIG. 5 , in accordance with this embodiment, inner terminals  310  are electrically and physically connected to MEMS terminals  220  and ground terminals  212  by electrically conductive solder columns  502 . Solder columns  502  extend from inner terminals  310 , through molded ring  220 , and to MEMS terminals  220  and ground terminals  212 . Inner terminals  310  are electrically connected in a one to one relationship to MEMS terminals  220  and ground terminals  212  by solder columns  502 . 
     For example, referring now to  FIGS. 1 and 5  together, solder balls (not shown) are formed on MEMS terminals  220  and ground terminals  212 . These solder balls are placed within via apertures  346  of molded ring  320  and on outer via surfaces  344  of through vias  338  (via apertures  346 , outer via surfaces  344 , and through vias  338  are illustrated in  FIG. 1 ). The assembly is then heated to reflow, i.e., heat to a melt and then cool to resolidify, these solder balls and through vias  338  to collectively form solder columns  502  as illustrated in  FIG. 5 . 
     In accordance with this embodiment, solder columns  502  include one or more ground solder columns  504  and one or more MEMS solder columns  506 . More particularly, ground solder columns  504  and MEMS solder columns  506  are identical in structure, i.e., are first and second sets of solder columns  502 . However ground solder columns  504  are electrically connected to ground plane  214  of base assembly  102 . In contrast, MEMS solder columns  506  are connected to MEMS electronic component  222  and/or converter electronic component  238  of base assembly  102 . 
     Base assembly mounting adhesive  106 , e.g., an underfill type dielectric material, surrounds and protects solder columns  502  in one embodiment. 
       FIG. 6  is a cross-sectional view of a molded cavity substrate MEMS package  600  in accordance with one embodiment. Molded cavity substrate MEMS package  600  of  FIG. 6  is similar to molded cavity substrate MEMS package  100  of  FIG. 1  and only the significant differences are described below. 
     Referring now to  FIG. 6 , in accordance with this embodiment, ground plane  214  is formed on outer surface  306  of substrate  302  of a molded cavity substrate  104 A. Further, outer traces  312  are formed on outer surface  206  of substrate  202  of a base assembly  102 A. 
     Ground plane  214  is electrically connected to vias  314 , inner terminals  310 , and ground vias  348 . Note that all the electrically conductive through vias  338  that extend through molded ring  320  in accordance with this embodiment are electrically connected to ground plane  214  and thus are referred to as ground vias  348 . 
     Outer traces  312  are electrically connected to vias  216  and inner traces  210 . Outer traces  312  are also electrically connected to vias  216  and ground terminals  212 . Ground terminals  212  are electrically connected to exposed outer via surfaces  344  of ground vias  348  by base assembly mounting adhesive  106 . However, in another embodiment, inner terminals  310  are directly connected to ground terminals  212  by solder columns similar to solder columns  502  of molded cavity substrate MEMS package  500  of  FIG. 5  as described above. 
       FIG. 7  is a cross-sectional view of a molded cavity substrate MEMS package  700  in accordance with one embodiment. Molded cavity substrate MEMS package  700  of  FIG. 7  is similar to molded cavity substrate MEMS package  600  of  FIG. 6  and only the significant differences are described below. More particularly, molded cavity substrate MEMS package  700  is formed without ground plane  214  and the associated conductors of molded cavity substrate MEMS package  600 . Accordingly, outer traces  312  are connected only to inner traces  210  by vias  216 . 
     Referring now to  FIG. 7 , molded ring  320  has an absence of through vias or other electrically conductive structures. Principal surface  324  of molded ring  320  is attached to inner surface  204  of substrate  202  by base assembly mounting adhesive  106 . 
     Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of the invention is at least as broad as given by the following claims.