Abstract:
By adding light reflective and/or transparent and/or translucent material within a micro-electronic circuit housing, improved light transfer is achieved between a light generation source and a light utilization device. In one embodiment, the reflective material is placed on the inside surface of a non-metallic housing lid and the light from the light source (typically an LED) reflects from the reflective material and impacts the device (typically an FET). In another embodiment, the LED and FET are encased in a clear (low light-loss) material (typically silicone overcoat) so as to allow the light from the LED to reflect from the top of the clear material onto the FET. If desired, an opaque encapsulant surrounds the clear material and fills out the volume within the housing. In another embodiment, clear or translucent (as opposed to opaque) encapsulant can be used to serve dual purpose as both the structural (volume filling, defined package share/outline) agent as well as to permit the internal light transmission and reflections to illuminate the device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present invention is a continuation-in-part of U.S. patent application Ser. No. 11/007,359, filed Dec. 8, 2004, entitled “LOW COST HERMETIC CERAMIC MICROCIRCUIT PACKAGE,” to which priority is hereby claimed and which is hereby incorporated by reference herein. The present application is related to concurrently filed, co-pending, and commonly assigned U.S. patent application Ser. No. XX/XXX,XXX, Attorney Docket No. 10060070-1, entitled “DUAL PATH ATTENUATION SYSTEM,” the disclosure of which is hereby incorporated herein by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates to non-metallic microcircuit packages and more particularly to systems and methods for making and using low cost microcircuit packages having internal light enhancement.  
       BACKGROUND  
       [0003]     In many situations it is desirable to combine a light source, such as an LED, within the same package as an electronic circuit. For example, it has been found that Gallium Arsenide (GaAs) Field Effect Transistors (FETs) have better switching performance when they are subjected to high intensity light during the switching operation. This enhanced performance stems from a decrease in the “slow tail effect” when the FET is operated in the presence of light. U.S. Pat. No. 5,808,322, issued Sep. 15, 1998, illustrates a high intensity light integrated with a GaAs FET switch for use in microwave test equipment. U.S. Pat. No. 6,876,271, issued Apr. 5, 2005, illustrates a light source mounted within the same chamber as a FET for use as a damping circuit. Both of these patents are hereby incorporated by reference herein.  
         [0004]     In U.S. Pat. No. 5,808,322, the LEDs are mounted to a small pc board that gets mounted to the back side of a carrier pc board. The carrier pc board has holes strategically placed to allow LED light to shine through the holes to the top side of the carrier pc board where another pc board is mounted upside down so that the switches are placed right over the holes. Thus light shines on the GaAs FET attenuator switches through the carrier pc board holes, directly impacting the FETs, thereby imparting increased performance (by way of faster switching times) to the FETs.  
         [0005]     In U.S. Pat. No. 6,876,271, the LED is mounted on a circuit board and is placed above the FET so that the light from the LED will directly impact the FET, thereby imparting increased performance (by way of faster switching times) to the FET.  
         [0006]     An older alternate arrangement, for example the arrangement shown in Agilent Part Number 5087-7137, has demonstrated that LEDs can be mounted on the same plane with the FET switch within a metal microcircuit enclosure having a metal lid. The light from the LED (which is directed upward and away from the FET) is reflected from the inside of the top of the metal enclosure and impacts the FET. Such an arrangement works well, but requires a metal housing to achieve the proper light transfer. In addition, such packages have used unpackaged LED die for mounting within the enclosure. Metal enclosures are large and expensive to manufacture and in many situations it is desirable to use smaller ceramic and/or plastic enclosures.  
         [0007]     For example, one packaging arrangement called a Quad Flat No Lead (QFN) package, is essentially a conductive lead frame on which is mounted the electronic circuitry. Such packages are manufactured in high volumes and at relatively low cost and size as compared to traditional metal and/or ceramic housings. An opaque (usually black) encapsulating material is placed around the electronic elements to fill out the volume within the enclosure. This material, in addition to providing support and stability to the electronic devices, acts to inhibit light transfer from the light source to the other elements, thus preventing the use of low cost non-metallic housings for applications that depend upon good light transfer for proper operation.  
       SUMMARY  
       [0008]     By adding light reflective and/or transparent and/or translucent material within a micro-electronic circuit housing, improved light transfer is achieved between a light generation source and a light utilization device. In one embodiment, the reflective material is placed on the inside surface of a non-metallic housing lid and the light from the light source (typically an LED) reflects from the reflective material and impacts the device (typically an FET). In another embodiment, the LED and FET are encased in a clear (low light-loss) material (typically silicone overcoat) so as to allow the light from the LED to reflect from the top surface of the clear material onto the FET. If desired, an opaque encapsulant surrounds the clear material and fills out the volume within the housing. In another embodiment, clear or translucent (as opposed to opaque) encapsulant can be used to serve dual purpose as both the structural (volume filling, defined package shape/outline) agent as well as to permit the internal light transmission and reflections to illuminate the device. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:  
         [0010]      FIG. 1  shows one embodiment of a low cost hermetically sealable package lid;  
         [0011]      FIG. 1A  shows a cross-section of the package lid of  FIG. 1 ;  
         [0012]      FIG. 1B  shows a cross-section of a ceramic package substrate with a lid on top fitted against the substrate to form a package;  
         [0013]      FIG. 1C  shows the inventive concepts contained within a generic plastic molded surface mount package;  
         [0014]      FIG. 2  shows one embodiment of an electronic circuit to be covered by the package lid of  FIG. 1 ;  
         [0015]      FIG. 3  shows one embodiment of a substrate having several electronic circuits and other components mounted thereon;  
         [0016]      FIGS. 4A and 4B  show side and top views, respectively, of an alternative embodiment contained within a molded plastic Quad Flat No Lead package; and  
         [0017]      FIG. 5  shows one embodiment of a circuit using the concepts of this invention. 
     
    
     DETAILED DESCRIPTION  
       [0018]      FIG. 1  shows a bottom view of one embodiment  100  of a low cost hermetically sealable package lid. In this embodiment, package lid  100  is a ceramic housing, or cover, designed to be placed over a microcircuit, such as RF microcircuit  202 , shown in  FIG. 2 .  
         [0019]      FIG. 1A  shows a cross-section view of package lid  100  taken through section  1 A of  FIG. 1  showing inside surfaces  102  and  104  which will be sealed. The height of sides  102  can be made to fit over circuits  202  and  206 - 3  ( FIG. 2 ) and can be made any height as required. A metallic bonding material, such as, for example, solder bead  103 , is shown on edge  101  and this bead could be on the outside edge as shown, or on the inside edge, or could be flat along the full edge. Alternatively, the lid could be attached with epoxy if full hermeticity protection is not needed for reliable circuit operation and part lifetime.  
         [0020]     The inside surface, including surfaces  104  and  102  of package lid  100 , in one embodiment, is coated with a ceramic dielectric material which is then fired at a temperature of 1250° C. for one minute. Currently, the dielectric material being used is applied by Max Levy Autograph, Inc., 220 West Roberts Avenue, Philadelphia, Pa.; and is a material proprietary to Max Levy Autograph, Inc. Any glaze of any color could be used and if increased reflectivity is desired the glaze could be clear or otherwise made reflective.  
         [0021]     A gold binding material, such as a ceramic gold mixture, is put on (by screening, sputtering, or otherwise) the bottom edges  101  and the package is again fired, this time to a temperature of 850° C. for one minute. The gold/tin solder  103  is put over the gold binding and the package lid is again fired, this time at 320° C. Note that gold/tin solder can be any material provided it will bond with the gold plated (or other) material of electronic circuit substrate  201  ( FIG. 2 ) in a manner to avoid water vapor from penetrating the seal. Since in our example electronic circuit  202  is assumed to be mounted on a gold plated platform, such as platform  201  ( FIG. 2 ), then solder bead  103  (shown best in  FIG. 1A ) could be gold/tin having a ratio of 80% gold to 20% tin. Alternatively, instead of applying the solder to the package lid, a separate solder preform could be used with a package lid to make the hermetic seal to the package substrate.  
         [0022]     Edges  101  of package  100  are then brought into contact with substrate  201  between the broken line and the edge of substrate  201  as shown in  FIG. 2 . The metal (in this example, gold/tin) is bonded with the gold plating of the substrate at a temperature of 300° C.  
         [0023]     One method of accomplishing such bonding is to bring the two pieces ( 100  and  200 ) into contact with one another in a carbon holding fixture and then applying electricity to the package. A weight can be used to force ceramic package lid  100  into better contact with substrate  201 . The electricity heats the package and solder  103  from the ceramic package bonds with the gold plating of substrate  201 . Note that the composition of the solder material on the lid controls the melting point of the seal and can be adjusted as necessary. Soldering, or other bonding, such as laser welding, brazing, welding, etc., of package  100  to substrate  201  should be performed in a dry nitrogen (or other drying) atmosphere. The assembled package should be tested for both gross and fine leakage. Note that it is also possible to obtain a hermetic seal by a low temperature glass being placed between a ceramic lid and a ceramic package.  
         [0024]     Using this system, the clear seal inside the ceramic package allows internal LED light (for example, from LED  206 - 3 ,  FIG. 2 ) to be reflected onto GaAs device  202  ( FIG. 2 ), if desired, thereby increasing operating system performance.  
         [0025]     The reason for glazing the inside surface of package lid  100  is to prevent moisture from wicking through the ceramic. Until recently it has been thought that the ceramic package lid itself was water tight. In actuality, a typical ceramic package lid is sufficiently grainy so as to allow water molecules to pass through. This realization has led to the glazing of inner surfaces of package lid  100 . If desired, the outer surface could be glazed instead, or both inner and outer surface could be glazed and, if desired, reflective material added to further increase the reflectivity inside the package.  
         [0026]      FIG. 1B  shows a cross-section illustration of the ceramic package substrate. The lid  100  is on top and fitted against substrate  105  to form a sealed package  110 . LED  206 - 3  is mounted on substrate  105  and emits light  113  from its top surface which light reflects from top surface  104  of lid  100 . The reflected light impacts electronic device  202  which also is mounted to substrate  105 . The inside of top surface  104  can be non-metallic but naturally reflective or could be coated to increase reflectivity. The top can be curved to direct the reflected light, if desired. In this example, as well as in the other examples discussed herein, electronic device  202  is a GaAs FET switch, but could be any type of device, including but not limited to devices constructed from GaAs, GaN or InP. While an FET device is shown, more complicated integrated circuits can be used. In some operations, the LED will remain on all the time, while in other operations the LED will only come on (perhaps for about 100 microseconds) when it is required for enhancing the operation of the electronic circuit. As will be discussed below, a clear encapsulant can be used instead of dry nitrogen so that light from LED  206 - 3  reflects off the top surface interface of the clear encapsulant onto the GaAs FET switch.  
         [0027]     In the example of  FIG. 1B , LED  206 - 3  (or as shown in  FIG. 1C , LED  122 ) emits light in the red frequency range, but the light can be in any frequency range, across frequencies and can be either visible or invisible to the naked eye. In most situations, the light will be trapped within the device due to reflection off the inside top surface or the top surface interface of any clear encapsulant, but for some purposes it may be desirable to allow at least a portion of the light to escape. An example of letting some light escape would be to provide a visual indication that the light is on and functioning correctly.  
         [0028]     Lid  100  can be a ceramic or plastic surface that can be coated on either the inside or the outside (or both) by a reflective (or partially reflective) material. This reflection can be added on the outside, for example, by silk screening, or by adhering a reflective (perhaps silvered) material to the surface. A low loss (at least low loss to the light frequency of interest) encapsulant could be positioned between LED  206 - 3  (and any other LED that is used) and top surface  104 . The encapsulant serves to hold the electronic devices in place. Note that, if desired, lenses (not shown) can be added to more accurately pinpoint the light if desired. Note that the top surface can be shaped (not show) to focus reflected light onto GaAs FET switch circuitry. The light from the LED can either be focused by transmission through the lens or other material or by reflection off the lens or by both methods.  
         [0029]     The cathode of the LED in the example of  FIG. 1B  is connected to ground via contact with substrate  105  while the anode is connected to an externally available terminal via bond wire  111 . Similarly, device  202  is connected to the substrate and to one or more bond wires  112 . Alternately, one terminal of a surface mount LED can be connected to the substrate ground  201 , and the other terminal of the LED can be connected to a substrate trace  203 , as shown in  FIG. 2 . this eliminates the need for bond wire  111 .  
         [0030]      FIG. 1C  illustrates an embodiment of the invention as applied to any generic plastic molded surface mount package  120 .  FIG. 1C  shows a cross-sectional view of the package with the GaAs (GaN, InP, etc.) device  121  and bare die LED  122  mounted to die paddle  123  with joining material  128  that would typically be conductive epoxy or a solder alloy. Device  121  and LED  122  are additionally connected to package I/O leads  124  with wire bonds  125  and  130 . It should be noted that the package I/O leads could very well be trimmed flush as in the case of many lead-less packages. Typical low cost molded parts would use an opaque (usually black) encapsulant  126 . The molded encapsulant provides protection and mechanically holds together the devices, die paddle, I/O leads, etc. as a fixed assembly and defines the final physical shape of the package.  
         [0031]     The embodiment of  FIG. 1C  uses a clear or translucent (rather than opaque) encapsulant  126  to allow for light transmission  124  inside the package. Light from light source (LED)  122  is reflected at the top of the package due to the difference in the index of refraction at the bondary between clear encapsulant  126  and reflective surface coating  127  and impacts the device  121 . It should be noted that there are many options for the reflective surface coating  127  such as: metalized or glazed coating, silkscreen or dye coating, patterned or matte surface finish, or in some cases outside air. The exact type of reflective surface coating chosen is based on cost and performance considerations.  
         [0032]     The light transfer zone can be a solid lens type material, where the light is focused onto the electronic switching device, or the clear overcoat could be constructed to act not only as a light transmission medium but also as a lens to help focus and increase the light that impacts the switching device. If desired, the clear overcoat can be used for the entire encapsulant, thus allowing the light to reach the top, and/or side, surface and possibly even reflect back.  
         [0033]     Additional types of packages in addition to commercially available ceramic packages can be used. These packages include Surface Mount (SMT) packages with adequate internal height, standard available SMT packages with increased height to reflect the LED light, plastic packages with lids that are heat welded on, leadless packages with the appropriate lid, and laminate packages. The clear/translucent overcoat or encapsulation implementation makes this approach applicable for many small, lower cost, plastic and chip scale packages. The packaging eliminates the need for air cavity packages thereby further reducing package height constraints and making it suited to high volume, low cost applications. The use of the overcoat protects the die and wire bonds from moisture, particulate contamination, and physical damage. Note that most plastic packages are not truly hermetic. If the GaAs FET switches and other GaAs IC circuitry are not well passivated to keep them moisture proof, then the hermetic package will have the longest mean time to failure in instrument applications. Some instrument applications require the hermetic package and other applications can be satisfied by the plastic packaged parts.  
         [0034]     This technology will work well with both laminate and plastic SMT packages without microwave shielded enclosures. Not having shielding (metal walls) allows microwaves to escape instead of reflecting. This allows the packaged part to not have resonances so they function better at high frequencies. Microwave signals leaking out are easily damped out on the pc board assembly structure with its assembly cover.  
         [0035]     As will be discussed below, the concepts discussed herein will work well for speeding up switching used in attenuators and speeding up switching in sending a signal between two or more ports.  
         [0036]     This packaging arrangement also lends itself to low cost assembly. The standard surface mount (SMT) LEDs, or bare die LEDs, are placed on the substrate with conductive epoxy or solder at the same time that the GaAs (or other device) die is attached to the same substrate. In the case of the QFN package or any other plastic package, bare die chip LEDs are placed and wire bonded to the package lead frame at the same time as the GaAs die. The SMT or bare die LEDs and GaAs devices can be placed in the package without compromising RF package performance. The LEDs can remain on, if desired, to provide a small amount of heat, which can prolong the life of the GaAs switch in a non-hermitic package, by helping to keep moisture out.  
         [0037]      FIG. 2  shows one embodiment  200  of an electronic device, such as electronic device  202 , to be covered by package lid  100 . Solder preform  103 , as discussed above, could be on the outside edge of package lid  100 , as shown, or on the inside edge (not shown), or across the entire edge (not shown). The inner edge of package lid  100  mates with substrate  201  along dotted line  205  thereby covering (protecting) circuit  202  and its various elements  203  from mechanical damage as well as from moisture. Connected within the package are LEDs  206 - 1 ,  206 - 2 ,  206 - 3  used as discussed above. Note that while three such light sources are shown, any number can be used, based only on the light intensity desired to impact the FET or other electronic device.  
         [0038]     Electronic device  200 , with package lid  100  soldered in place, then can be added to a printed circuit board or to another substrate, if desired, (such as substrate  301 ,  FIG. 3 ) using a solder compound requiring less heat, for example 230° C., to control the soldering process. The solder used for such a bonding could be, for example tin/lead. The new RoHS (lead free) solders also will work well, requiring 260° C. to make the bond.  
         [0039]      FIG. 3  shows one embodiment  300  of a printed circuit board or a substrate, such as substrate  301 , having several electronic circuits, such as circuits  200 ,  302 , and components, such as components  303  mounted thereon. Components  200  are shown uncovered, while component  302  is essentially component  200  with package lid  100  sealed thereto. Substrate  301  could have terminals  304 , or flat planar terminals (not shown) for connection to other system components. The new RoHS (lead free) solders also will work well, requiring 260° C. to make the bond.  
         [0040]      FIG. 4A  shows a top view of the layout of microcircuit  403  having electronic device  401  and LED  402  positioned therein in a plastic molded Quad Flat No lead (QFN) package.  
         [0041]      FIG. 4B  is a cross-sectional view of the package of  FIG. 4A . The opaque encapsulant (molding compound)  406  gives rigidity to and defines the outline of package  400 . Note that the implementation is not limited to the QFN style package, but rather is applicable to any low cost, molded plastic package. In this embodiment clear seal  411  (typically a silicone die overcoat) is applied over device  401  and LED  402  prior to molding with an opaque (black in this instance) molding compound (encapsulant)  406 . An alternative embodiment, as shown in  FIG. 1C , would be to use a clear or translucent molding (encapsulant) compound, thus eliminating the need for the extra clear die overcoat. Ground is connected, for example via pins  1 ,  2 ,  4 ,  9 ,  10 , and  12 , to surface  403  on which LED  402  and device  401  are connected. Pin  11  via lead  404  controls the on/off condition of LED  402  and pins  6  and  15  supply ground to device  401 . Pins  5  and  16  (lead  404 ) control the operation of the switch, while pins  3  (lead  405 ),  7  (lead  404 ), and  14  are the signal terminals. Note that LED  402  can be on all the time or can be controlled by an external signal. Alternatively, LED  402  can be connected to device  401  so that when that device begins to switch, the LED, or any number of LEDs, light up to enhance the switching speed. Light  409  from light source (LED)  402  is reflected due to the difference in the index of refraction and angle of incidence at the boundary between the clear overcoat  411  and the opaque encapsulant  406  and impacts the device  401 .  
         [0042]     Note that devices  401  and  402  are shown mounted to the same substrate (as are the devices within the packages shown in  FIGS. 1B and 1C ). This is illustrated in this manner for simplicity but in actual practice one or more of the devices may be mounted slightly higher, for example, on a dielectric shelf. This then would make the base of the one element, for example, the LED, higher by perhaps about 0.25 mm than the base of one or more of the other elements. As used in the application, a device sitting higher than another device but ultimately physically connected to the same substrate (or to a separate substrate on the same plane as the first substrate) is considered to be coplanarly mounted with that other device. Devices mounted to separate substrates where the substrates lie in the same plane and approximately at the same elevation within a housing are also said to be coplanar.  
         [0043]      FIG. 5  shows one embodiment  50  of an attenuator that can be constructed using the concepts discussed above. Shown in  FIG. 5  is three segmented circuit  50  having segments  51 - 1 ,  51 - 2  and  51 - 3 . Each segment has one or more LEDs, such as LEDs  55 - 1 ,  55 - 2  and  55 - 3 , to assist the switching speed of switches  52 - 1  to  52 - 6  within the segment. The light also assists the switching speed of the attenuator ICs  53 - 1  to  53 - 5  since they too contain integrated switches. Note that the number of such LEDS can be different for each segment if desired, or could be different depending upon the device characteristics desired from time to time.  
         [0044]     Circuit  50  provides not only an extension of the electronic step attenuator&#39;s maximum frequency range to 6 GHz or above, but also circuit  50  adds no measurable distortion to the signal, while achieving the minimum possible insertion loss yielding the highest output signal level. Low insertion loss from the output step attenuator also means that for a given output power at the instrument&#39;s output connector, the output amplifiers will be operating at a lower RF power level, leading to lower distortion to the signal added by the output amps.  
         [0045]     In order to eliminate the output step attenuator as a contributor to the distortion of the signal, and to maximize the output power of the source by minimizing the insertion loss of the attenuator in its 0 dB state, circuit  50  has a two path topology. One path has the same arrangement of step attenuator ICs  53 - 1  to  53 - 5  as in the previous Multi-Chip Modules (MCM), while the second “high power” path consists of six low loss, low distortion SPDT GaAs FET switches  52 - 1  to  52 - 6 . This topology adds no measurable distortion to the output signals, while at the same time gives 4 dB lower loss in the 0 dB state at 6 GHz than using the previous step attenuator ICs, and does all of this using pre-existing ICs. The highest ˜10 dB of signal power goes through the high power path of the attenuator, with the power setting capability coming from the Automatic Level Control (ALC) of the source (not shown). When lower power levels are desired from the signal source, the ALC can be set to deliver signals of lower than ˜5 dB below the maximum power to the step attenuator, and the step attenuator can add any additional attenuation above that value. A circuit that operates in this manner has been available for several years packaged in a housing having at least one metal surface (a Lid).  
         [0046]     In order to provide a low cost packaging solution that is extendable to greater than 40 GHz without changing the packaging format and without using a metal housing, a packaging approach using the concepts discussed herein is achieved by dividing the step attenuator into three SMT laminate based 10 mm×10 mm (MCMs). The frequency performance of the PCB transmission line to package transitions used in these MCMs has been shown to give excellent performance to beyond 50 GHz, allowing for straightforward extensions of these 6 GHz MCMs to higher frequencies. The use of standardized low cost SMT assembly techniques, as discussed above, both for assembling the ICs in the package and the package to the PCB, allowed the cost of this solution to be lower than that of the previous MCM based solution used in the ESG sources, even with the additional SPDT ICs employed in this topology.  
         [0047]     The fast switching and settling time of the previous step attenuator was maintained by continuing the use of high intensity LEDs to illuminate the ICs to effectively eliminate the gate lag (slow tails) effect in the GaAs FET based switch ICs and step attenuator ICs. This effect works by the photons from the LED ejecting the electrons in traps at the GaAs surface near the FET gate, such that the traps are always nearly empty. Thus, there is no slow emptying of the traps when the FET is turned ON, and no change in channel conductance. With the use of the higher intensity, low cost SMT LEDs that have been developed in the last few years, and by selecting a dielectric lid (or other non-metallic reflective material) with a suitable optical reflectance, LEDs can be mounted on the package shelf (or slightly above the package shelf) with their light projected upward. The light reflected back down from a top surface is of suitable intensity and distribution to suppress the gate lag effects of the GaAs FETs in the ICs, while adding minimal cost to the solution. While one LED is shown in the drawing, three LEDs can be used in each module to make sure there are no dead spots in illumination over any of the ICs containing FETs.  
         [0048]     The extremely low loss and low distortion GaAs FET SPDT switches used in this topology have a maximum insertion loss of 0.5 dB at 6 GHz. With all six of these SPDT switches in series, there is about 4 dB less insertion loss at 6 GHz than the insertion loss of the five step attenuator ICs in series in their 0 dB states at 6 GHz. The isolation of each switch in its OFF state of greater than 30 dB for frequencies to 6 GHz is sufficient to give the necessary isolation under the most stringent conditions of when the step attenuator is set to its 130 dB state. The larger size of the FETs on these switch ICs compared to the FETs used on the step attenuator ICs, particularly the 40 dB step attenuator IC, are what allow for the improved distortion performance of the two path approach used in this solution.  
         [0049]     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, as new epoxy glues and plastic molding compounds become available it is possible that they have increased moisture resistance. Some of these epoxies can then be used to attach the glazed package lid to the package substrate, achieving much better moisture resistance than previously possible. Such a package lid may not be able to achieve hermetically, as defined above, but may be entirely appropriate for electronic circuit protection in some instances. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.