for the purpose of promoting an understanding of the principles of the disclosure , reference will now be made to the embodiments illustrated in the drawings and described in the following written description . it is understood that no limitation to the scope of the disclosure is thereby intended . it is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the disclosure as would normally occur to one of ordinary skill in the art to which this disclosure pertains . fig1 depicts a mems microphone assembly 100 . the mems microphone assembly 100 includes a mems die 102 supported on a water resistant substrate 104 and encased in a plastic overmold 106 . a cap 108 is positioned over a back - cavity 110 of the mems die 102 . the mems die 102 further includes a downwardly extending copper pillar ring 112 shown in additional detail in fig2 - 5 . at a lower distal end of the copper pillar ring 112 a solder pillar ring 114 is provided on a lower surface of the copper pillar ring 112 . in some embodiments , the solder pillar ring is positioned at an upper surface of the copper pillar ring . the solder pillar ring 114 is used to attach the mems die 102 to the substrate 104 as discussed in further detail below . the mems die 102 further includes four i / o posts 116 , 118 , 120 , and 122 . each of the i / o posts 116 , 118 , 120 , and 122 includes an upper copper post 126 , 128 , 130 , and 132 and a lower solder post 136 , 138 , 140 , and 142 . the i / o posts 116 , 118 , 120 , and 122 provide for electrical connection points between the mems die 102 and the substrate 104 . in different embodiments , more or fewer i / o posts are included . returning to fig1 , the substrate 104 is a multiple layer substrate . the bottom layer of the substrate 104 is a solder mask layer 150 . a metal layer 152 is located on an upper surface of the solder mask layer 150 . a pre - impregnated ( pre - preg ) organic layer 154 is located between the metal layer 152 and another metal layer 156 . each of the lower layers 150 , 152 , 154 , and 156 are perforated to form a lower acoustic port 158 which terminates at a water resistant membrane 160 . the opening in the solder mask layer 150 and the metal layer 152 are larger than the openings in the other layers 154 and 156 to allow for a metal acoustic seal ring ( pad ) 162 positioned on the lower surface of the pre - preg organic layer 154 as further shown in fig6 . also shown in fig6 are four package i / o pads 164 . typically , the acoustic seal ring 162 and the i / o pads 164 are formed from the metal layer 152 . returning to fig1 , above the water resistant membrane 160 , a pair of metal layers 166 and 168 sandwich an upper pre - preg organic layer 170 . an upper solder mask layer 172 is located on the upper surface of the metal layer 168 . each of the upper layers 172 , 166 , 168 and 170 are perforated to form an upper acoustic port 174 which terminates at the water resistant membrane 160 . the upper acoustic port 174 is aligned with the lower acoustic port 158 . with reference to fig7 , four wells 180 , 192 , 184 , and 186 are formed through the upper solder mask layer 172 to expose portions of i / o pads 188 , 190 , 192 , and 194 formed in the metal layer 168 . a ring trench 196 is also formed through the upper solder mask layer 172 and the metal layer 168 to expose a ring of the pre - preg organic layer 170 and form a metal ring 171 . fabrication of the mems microphone assembly 100 is substantially accomplished using any desired fabrication processes . for example , electrical connections for the i / o pads 164 and the i / o pads 188 , 190 , 192 , and 194 can be provided within the substrate 104 by the drilling of vias that are then filled with conductive epoxy or lined and plated using standard pcb via plating techniques . likewise , the layers of the substrate 104 are sandwiched using any desired process . in at least one embodiment , however , the substrate 104 includes the water resistant membrane 160 . the water resistant membrane 160 is an acoustically transparent breathable material which restricts the passage of moisture therethrough . in one embodiment , the water resistant membrane 160 is formed from polytetrafluoroethylene ( ptfe ). accordingly , fluid is hindered from moving into the mems die 102 through the acoustic ports 158 and 174 . one difference from known devices is the formation of the metal ring 171 using the ring trench 196 through the upper solder mask layer 172 and the metal layer 168 . the ring 171 is configured to attach to the copper pillar ring 112 using the solder pillar ring 114 as depicted in fig1 during a flip - chip assembly process . the copper pillar ring 112 and solder pillar ring 114 are formed , for example , using a modification of a process described in u . s . pat . no . 6 , 681 , 982 which issued on jan . 27 , 2004 . the modified &# 39 ; 982 patent process is used in one embodiment to form the copper pillar ring 112 with a 80 μm height while the solder pillar ring 114 has a 20 μm height . the copper pillar ring 112 and the solder pillar ring 114 both have a 75 μm diameter . the i / o posts 116 , 118 , 120 , and 122 are each formed in like manner to the copper pillar ring 112 and solder pillar ring 114 . accordingly , when the mems die 102 is positioned on the substrate 104 during the flip - chip process , the lower solder posts 136 , 138 , 140 , and 142 are positioned through the respective wells 180 , 182 , 184 , and 186 and into contact with the respective i / o pad 188 , 190 , 192 , and 194 . additionally , the solder pillar ring 114 is positioned through the ring trench 196 and into contact with the ring 171 . the lower solder posts 136 , 138 , 140 , and 142 are then connected to the respective i / o pad 188 , 190 , 192 , and 194 using a reflow process . the solder pillar ring 114 is also connected to the ring 171 during the reflow process . the copper pillar ring 112 thus forms the microphone front volume in the finished assembly . the cap 108 is then positioned on the upper end of the mems die 102 ( see fig1 ) and the plastic overmold is overmolded onto the mems die 102 and the upper solder mask layer 172 . in some embodiments , the ring trench 196 is sufficiently larger than the copper pillar ring 112 so as to allow some of the plastic overmold 106 to flow into the well to provide increased bonding as depicted in fig1 . the mems microphone assembly 100 thus provides a water proof seal between the mems die and the substrate , which may further include a water proof membrane integrated into a substrate such that an acoustic port that is water proof / resistant may be implemented at the package level . this is achieved by bonding two substrate cores that have pre - drilled acoustic port holes over a water proof breathable membrane . in some embodiments , the water proof breathable membrane is provided in the form of an insert . by way of example , fig8 depicts a substrate 198 which is used in the mems microphone assembly 100 in place of the substrate 104 . the substrate 198 is a multiple layer substrate . the bottom layer of the substrate 198 is a solder mask layer 200 . a metal layer 202 is located on an upper surface of the solder mask layer 200 . a pre - preg organic layer 204 is located between the metal layer 202 and another metal layer 206 . each of the layers 200 , 202 , 204 , and 206 are perforated to form a lower acoustic port 208 which terminates at a water resistant membrane 210 . the opening in the solder mask layer 200 and the metal layer 202 are larger than the openings in the other layers 204 and 206 to allow for a metal acoustic seal ring ( pad ) 212 located on the lower surface of the pre - preg organic layer 204 . above the water resistant membrane 210 , a pair of metal layers 216 and 218 sandwich an upper pre - preg organic layer 220 . an upper solder mask layer 222 is located on the upper surface of the metal layer 218 . each of the layers 216 , 218 , 220 and 222 are perforated to form an upper acoustic port 224 which terminates at the water resistant membrane 210 . the upper acoustic port 224 is aligned with the lower acoustic port 208 . a ring trench 226 is formed through the upper solder mask layer 222 to expose a metal ring 227 , and wells , vias , and i / o ports ( not shown ) are also provided . the substrate 198 is thus substantially the same as the substrate 104 , and is assembled to the mems die 102 in like manner as the substrate 104 . the main difference is that instead of a membrane layer , the water resistant membrane 210 is formed as an insert within a substrate core 228 . both lower substrates allow for the provision of electrical connection between the top and bottom substrates in any desired manner such as by laser or mechanical drilling of vias that are then filled with conductive epoxy or lined and plated using standard pcb via plating techniques . the mems microphone assembly 100 further incorporates a copper pillar ring plated onto the mems die forms . this ring forms a barrier for subsequent processes when the die has been bonded to the substrate / chip carrier . specifically , the ring forms an epoxy barrier during overmold processing of the microphone assembly . the mems microphone assembly 100 thus provides a new semiconductor package form factor that incorporates wafer proof / resistant characteristics and allows for overmolded package construction . the package design in some embodiments further addresses a need for integrating a water - proof membrane into the porthole of a mems microphone package to prevent moisture damage . additionally , the mems microphone assembly 100 provides a method for using a copper pillar seal ring to create a defined front volume that is compatible with epoxy overmold processes that are common to standard semiconductor packages . while the disclosure has been illustrated and described in detail in the drawings and foregoing description , the same should be considered as illustrative and not restrictive in character . it is understood that only the preferred embodiments have been presented and that all changes , modifications and further applications that come within the spirit of the disclosure are desired to be protected .