阅读说明：本技术 模制的空气腔封装及包括该封装的装置 (Molded air cavity package and device including the same ) 是由 伦纳度斯·希德罗瑞斯·玛莉亚·拉本 方济各·格拉尔杜斯·玛莉亚·梅乌森 简·约瑟夫·布里奥尼斯· 于 2021-06-04 设计创作，主要内容包括：本发明涉及模制的空气腔封装及包括该封装的装置。本发明特别涉及用于射频“RF”应用(包括但不限于RF功率放大器)的模制的空气腔封装。作为使用以连续的方式围绕封装的整个周边布置的硬止动特征的替代,本发明提出使用由第一盖支撑元件和第二盖支撑元件形成的间隔开的柱。通过仅使用有限数量(例如三或四个)的柱,能够以更可预测的方式限定盖相对于主体的位置。这在柱布置在封装的外边角的情况下尤其适用。(The invention relates to a molded air cavity package and a device including the same. The present invention particularly relates to molded air cavity packages for radio frequency "RF" applications, including but not limited to RF power amplifiers. Instead of using hard stop features arranged in a continuous manner around the entire perimeter of the package, the present invention proposes to use spaced apart columns formed by a first lid support element and a second lid support element. By using only a limited number of posts, for example three or four, the position of the cover relative to the body can be defined in a more predictable manner. This is particularly true where the posts are disposed at the outer corners of the package.)

1. A molded air cavity package comprising:

mounting a substrate;

a semiconductor die mounted on the mounting substrate;

a plurality of package contacts, each package contact having a respective package contact end;

a body formed of a cured molding compound, wherein the body comprises a lower portion and an upper portion integrally connected to the lower portion;

wherein the lower portion is fixedly connected to the mounting substrate and the package contact;

wherein the package contact end of each package contact is free of the cured molding compound and is electrically connected to the semiconductor die;

the molded air cavity package further comprises a cover having a cover base and cover sidewalls projecting from edges of the cover base toward the upper portion, the cover sidewalls fixedly attached to the upper portion using an adhesive, wherein the cover, the body, and the mounting substrate define an air cavity;

wherein the lower portion has an inner region and an outer region relative to a center of the package, and the molded air cavity package further comprises a plurality of individual first cover support elements formed in one of the inner region and the cover base and a plurality of individual second cover support elements formed in the other of the inner region and the cover base, wherein each first cover support element extends toward and abuts a respective second cover support element forming a respective post disposed in spaced relation to the upper portion and the cover sidewall.

2. The molded air cavity package of claim 1, wherein the surfaces of the upper portions facing the cover sidewalls and the surfaces of the cover sidewalls facing the upper portions together define a channel in which adhesive is disposed, the channel starting at the cavity and an outlet located on an outer surface of the package, the adhesive blocking the channel to provide an air-tight seal of the package;

wherein the channel is preferably wider towards its outlet when viewed from the interior of the chamber.

3. The molded air cavity package of any of the preceding claims, wherein the body secures the plurality of package contacts in a spaced apart manner relative to the mounting substrate, thereby electrically isolating the plurality of package contacts from the mounting substrate, and wherein the upper portion forms a ring integrally connected to an outer region of the lower portion;

wherein, preferably:

each of the package contacts comprises a lead and each of the package contact ends comprises a lead end, wherein a plurality of the leads extend through the body of the cured mold compound, wherein each of the lead ends is supported on or embedded in a support surface of the inner region of the lower portion, the molded air cavity package further comprising a bond wire for connecting the lead end to the semiconductor die, wherein, for each lead, the support surface preferably comprises a recess in which the respective lead is at least partially received, and wherein, more preferably, an upper surface of each of the leads is coplanar with a remainder of the support surface; and

the plurality of individual first cover support elements are formed in one of the support surface of the interior region and the cover base, and the plurality of individual second cover support elements are formed in the other of the support surface of the interior region and the cover base.

4. The molded air cavity package of claim 3, wherein at least one of the first cover support elements is formed in the support surface of the interior region and integrally connected to the body, and wherein the respective second cover support element is formed in the cover base and integrally connected to the cover base;

wherein preferably the lid base is quadrilateral in shape and wherein some of the second lid support elements are formed in respective corners of the lid base spaced from the side walls, and wherein more preferably the plurality of second lid support elements comprises three second lid support elements and each second lid support element is arranged in a respective corner of the lid base, and preferably comprises four second lid support elements.

5. The molded air cavity package of claim 3, wherein at least one of the second cover support elements is formed in the support surface of the interior region and integrally connected to the body, and wherein the respective first cover support element is formed in and integrally connected to the cover base;

wherein preferably the lid base is quadrilateral in shape and wherein some of the first lid support elements are formed in respective corners of the lid base spaced from the side walls, and wherein more preferably the plurality of first lid support elements comprises three first lid support elements and each first lid support element is arranged in a respective corner of the lid base, and preferably comprises four first lid support elements.

6. The molded air cavity package of any one of claims 3-5, wherein each second lid support element is formed by a non-recessed and non-protruding area of the support surface of the interior region or by a non-recessed and non-protruding area of the lid base, wherein preferably the non-recessed and non-protruding area is flat.

7. The molded air cavity package of claim 3, wherein the molded air cavity package is a land grid array package, wherein the mounting substrate comprises a printed circuit board, wherein the package contacts each comprise a respective land formed on an outer surface of the printed circuit board, the package contacts each further comprise a land formed on an inner surface of the printed circuit board, the lands forming respective package contact terminals;

wherein preferably the semiconductor die is flip-chip mounted to the printed circuit board using the pads formed on the inner surface of the printed circuit board, more preferably the molded air cavity package further comprises bond wires for connecting the package contact terminals to the semiconductor die.

8. The molded air cavity package of any one of claims 1-7, wherein each of the second cover support elements comprises a recess in which the corresponding first cover support element is received,

preferably, the plurality of second cover support elements comprises at least three second cover support elements:

wherein the shape of the recess of two of the at least three second cover support elements limits relative movement between the cover and the body in mutually different directions parallel to the mounting substrate during arrangement of the cover on the body, wherein preferably the recess of the second cover support elements comprises one of a groove and an elongated slot; or

Wherein the recesses of two of the at least three second lid support elements have a shape complementary to the shape of the respective first lid support elements such that: relative movement between the cover and body in all directions parallel to the mounting substrate is limited during placement of the cover on the body.

9. The molded air cavity package of any preceding claim, wherein an upper surface of the upper portion comprises one or more first alignment structures, and wherein a lower surface of the cover sidewall comprises one or more second alignment structures, wherein the first and second alignment structures are configured to cooperate during placement of the cover on the body to cause the cover and the body to move relative to each other to a position in which the first and second cover support elements abut each other.

10. An electronic device comprising the molded air cavity package of any of the preceding claims.

Technical Field

The invention relates to a molded air cavity package. Furthermore, the invention relates to a device comprising such an air cavity package. The present invention particularly relates to molded air cavity packages for radio frequency "RF" applications, including but not limited to RF power amplifiers.

Background

Some embodiments of a molded air cavity package according to the present invention have the structural features of the package schematically illustrated in fig. 1. More specifically, some embodiments of a molded air cavity package according to the present invention include a thermally conductive mounting substrate 1, for example in the form of a copper, aluminum, or other metal or alloy substrate. Alternatively, a laminate substrate, printed circuit board, or lead frame die pad may be used. A semiconductor die 2 is mounted on a thermally conductive mounting substrate 1 shown in fig. 1. Typically, a solder layer, glue layer or Ag frit layer (not shown) is used to mount the semiconductor die 2 to the mounting substrate 1. It is further noted that the semiconductor die 2 may be mounted using flip-chip die attach technology (flip-chip die attach). In this case, the printed circuit board may serve as a mounting substrate on which the semiconductor die 2 is flipped.

The molded air cavity package also includes a plurality of package contacts in the form of leads 3, each lead 3 having a respective lead end 3A. The leads 3 are configured for conveying electrical signals to and from the molded air cavity package. The leads 3 may be flat as shown in fig. 1, or the leads 3 may have a curved shape, sometimes referred to as gull-wing leads.

Typically, the lower surface 1A of the thermally conductive mounting substrate 1 is exposed on the outer surface of the molded air cavity package. The exposed surface 1A may be physically connected to a ground plane on a printed circuit board on which the molded air cavity package may be mounted. More specifically, the exposed lower surface 1A allows heat and current to pass through. Note that when a chip pad is used as a mounting substrate, then the exposure of the lower surface may not be applicable.

The molded air cavity package of fig. 1 also includes a body of cured molding compound that secures the plurality of leads 3 in a spaced-apart manner relative to the thermally conductive mounting substrate 1, thereby electrically isolating the plurality of leads 3 from the thermally conductive mounting substrate 1. The cured molding compound may be, for example, a thermoset material, such as Duroplast thermoset (Duroplast), or a thermoplastic material, such as a liquid crystal polymer. To manufacture a molded air cavity package, the leads 3 and the thermally conductive mounting substrate 1 are set in a mold while maintaining a predetermined distance. The molding compound in liquid form will be added to the mold using injection molding or transfer molding techniques, after which the molding compound will cure.

The body comprises a lower part 4 and an upper part 5 integrally connected to the lower part 4. Here, it should be noted that the terms "upper" and "lower" will be used throughout the description to indicate positions relative to the lower surface 1A of the thermally conductive mounting substrate 1. Similarly, when a die pad is used as a mounting substrate, its lower surface may be used as a reference.

The lower part 4 has an inner area 4A and an outer area 4B with respect to the center of the package. In all the figures, the boundary between the regions 4A and 4B is indicated by a broken line B. Further, the lower portion 4 is fixedly connected to the heat conductive substrate 1 and the lead wires 3. The upper part 5 forms a ring integrally connected to the outer region 4B of the lower part 4. A plurality of leads 3 extend through the body formed of cured molding compound. The lead end 3A of each lead 3 has no cured molding compound and is supported on the support surface 6 of the inner region 4A of the lower portion 4 or embedded in the support surface 6 of the inner region 4A of the lower portion 4. Generally, the upper surface of the lead terminal 3A is coplanar with the rest of the support surface 6.

The molded air cavity package also includes bond wires 7 for connecting the lead terminals 3A to the semiconductor die 2, or more specifically to one or more integrated circuits on the semiconductor die 2.

The molded air cavity package further comprises a lid 8, the lid 8 having a lid base 8A and lid side walls 8B that protrude from edges of the lid base 8A towards the upper portion 5. The lower surface 9 of the lid sidewall 8B is fixedly attached to the upper surface 10 of the upper portion 5 using an adhesive. In fig. 1, an adhesive (not shown) is disposed in a channel 12 defined by the upper surface 10 and the lower surface 9. In this manner, the cover 8, the body of cured molding compound, and the thermally conductive mounting substrate 1 define an air cavity 11 in which the semiconductor die 2 is disposed.

Packages of the above type provide a relatively low cost solution compared to ceramic packages in which a ceramic ring is used to secure the leads relative to a thermally conductive mounting substrate or die pad. It should also be noted that the term "air cavity package" does not exclude embodiments in which there is a gaseous mixture inside the cavity that is different from ambient air. Molded air cavity packages have the advantage of improved RF performance compared to such packages in which the interior of the package is completely filled with molding compound, since there are no dielectric losses within the molding compound covering the semiconductor die and/or the bond wires.

A general structure according to the preamble of claim 1 and as shown in fig. 1 is known from US 10199303B 1. In addition to the features shown in fig. 1, the embodiment of US 10199303B1 also includes a hard-stop feature defined in the upper surface 10 of the upper portion 5 and the lower surface 9 of the lid side wall 8B. The location of these hard stop features is indicated in FIG. 1 using arrows 13. As mentioned above, the upper surface 10 of the upper portion 5 and the lower surface 9 of the lid side wall 8B define a channel 12, and the adhesive used to join the lid 8 and the body is disposed in the channel 12. The hard stop features abut each other, thereby defining the package height and defining the volume of the channel 12. In addition, the hard stop feature closes the channel to prevent adhesive from flowing out of the package. It is claimed in US 10199303B1 that by defining the volume of the channel 12, the amount of adhesive used to ensure a sufficient seal can be better controlled.

In the embodiment of US 10199303B1, the upper surface 10 of the upper portion 5 and the lower surface 9 of the lid side wall 8B each further comprise an angled surface (not shown in fig. 1) capable of self-aligning the lid 8 relative to the body during attachment of the lid 8 to the body.

Fig. 2A shows a schematic top view of the package of fig. 1, showing some boundaries between different materials. For example, line a marks the outside of the package, line B marks the inside surface of the lid sidewall 8B and indicates the boundary between the regions 4A and 4B, and line C marks the periphery of the thermally conductive substrate 1.

A disadvantage of the package of US 10199303B1 is related to the warpage that is usually present in the lower part (e.g. the body) of the package. This problem is illustrated in fig. 2B, which fig. 2B schematically shows a side view of the package according to arrow D in fig. 2A. Here, the lower part of the package is collectively denoted by reference numeral 14. In practice, there may be some warpage or distortion in the lower portion 14. Since the hard stop features of known packages extend around the entire perimeter of the package, positioning lid 8 may result in lid 8 being in an unpredictable angular position relative to lower portion 14. This attitude may result in a large gap between the cover 8 and the lower portion 14. Such gaps may risk air leakage, thereby reducing the life of the package. Furthermore, the unpredictable attitude of the lid 8 relative to the lower portion 14 may result in the channel 12 having varying capacities on the package. This may lead to too much adhesive being present in the channel in certain poses, so that there is a risk of adhesive flowing inside the package, for example onto the lead terminals 3A, which may lead to field failure.

Disclosure of Invention

It is an object of the present invention to provide a molded air cavity package in which the above problems do not occur or at least do not occur to a lesser extent. According to the invention, this object is achieved with a molded air cavity package according to claim 1, which is characterized in that the lower part has an inner area and an outer area with respect to the center of the package, and that the molded air cavity package further comprises a plurality of individual first cover support elements formed in one of the inner area and the cover base and a plurality of individual second cover support elements formed in the other of the inner area and the cover base, wherein each first cover support element extends towards and abuts a respective second cover support element, thereby forming a respective pillar arranged spaced apart from the upper part and cover side walls.

Instead of using hard stop features arranged in a continuous manner around the entire perimeter of the package, the present invention proposes to use spaced apart columns formed by a first lid support element and a second lid support element. By using only a limited number of posts, for example three or four, the position of the cover relative to the body can be defined in a more predictable manner. This is particularly true where the posts are disposed at the outer corners of the package. Furthermore, by not arranging the first and second cover support elements in the upper or lower surface of the upper portion of the cover side wall, but in the cover base or inner area, a more reliable definition of the cover support elements may be achieved. More specifically, the applicant has found that the manufacturing tolerances of the lid base and the inner region are less than the manufacturing tolerances of the lower surface of the lid side wall and the upper surface of the upper portion. Further, by placing the hard stop feature away from the upper surface and the lid sidewall, more area is available for placement of adhesive, thereby improving the reliability of the seal.

The upper surface of the upper portion and the lower surface of the lid sidewall may collectively define a channel in which the adhesive is disposed. The channel may originate from the cavity and the outlet is located on an outer surface of the package. In addition, the adhesive blocks the channel, thereby providing a hermetic seal of the package. The channel may extend around a perimeter of the molded air cavity package. Further, the lower surface of the lid side wall and the upper surface of the upper portion preferably do not abut each other, but are connected only using an intermediate adhesive. In this way, the alignment of the cover with respect to the main body in the final position of the cover is achieved using only the first and second cover support elements.

Preferably, the channel is wider towards its outlet when viewed from the interior of the chamber. The purpose of this tapering is to encourage the adhesive within the channel to flow outwardly relative to the center of the molded air cavity package during the process of securing the cover to the body. In this way, the adhesive can be prevented from flowing into the cavity.

The cover may be made of the same or different molding compound as the body. For example, the molding compound of the cover and/or the body may comprise a thermoset compound, such as a laplace thermoset, or a thermoplastic compound, such as a liquid crystal polymer.

The body is capable of securing the plurality of package contacts in a spaced-apart manner relative to the mounting substrate to thereby electrically isolate the plurality of package contacts from the mounting substrate, and wherein the upper portion may form a ring integrally connected to an outer region of the lower portion; further, the package contacts may each comprise leads and the package contact ends may each comprise lead ends, wherein a plurality of leads extend through the body of cured molding compound, wherein each lead end is supported on or embedded in a support surface of the inner region of the lower portion. The molded air cavity package may further include bond wires for connecting the lead ends to the semiconductor die. In this case, the plurality of individual first cover supporting elements are formed in one of the supporting surface of the inner region and the cover base, and the plurality of individual second cover supporting elements are formed in the other of the supporting surface of the inner region and the cover base.

For each lead, the support surface includes a recess in which the respective lead is at least partially received. Typically, the lead terminals are pressed onto the mold during the molding process. Where no leads are present, the mold compound will be disposed. Thus, in some embodiments, the upper surface of each lead will be coplanar with the rest of the support surface.

At least one of the first cover support elements (preferably all first cover support elements) may be formed in the support surface of the interior region and may be integrally connected to the body, and the respective second cover support element may be formed in the cover base and may be integrally connected to the cover base. Further, the cover base may be quadrilateral in shape, such as square or rectangular, and some of the second cover support elements may be formed in respective corners of the cover base spaced from the cover side walls. The plurality of second cover support elements comprises three of said second cover support elements and each of said second cover support elements is arranged in a respective corner of said cover base, and preferably comprises four of said second cover support elements.

Alternatively, at least one of the second cover support elements may be formed in the support surface of the interior region and may be integrally connected to the body, and the respective first cover support element may be formed in the cover base and may be integrally connected to the cover base. Further, the cover base may be quadrilateral in shape, and some of the first cover support elements may be formed in respective corners of the cover base spaced from the cover side walls. The plurality of first cover support elements comprises three of said first cover support elements and each of said first cover support elements is arranged in a respective corner of said cover base, and preferably comprises four of said first cover support elements.

Each of the second cover support elements may be formed by a non-recessed and non-protruding region of the support surface of the inner region, or by a non-recessed and non-protruding region of the cover base. Preferably, the non-recessed and non-protruding areas are flat.

Each of the package contacts includes a signal pad having an inward surface forming a corresponding package contact end. In this case, the molded air cavity package further includes bond wires for connecting inward surfaces of the signal pads to the semiconductor die. The molded air cavity may be one of a quad flat no-lead package, a power quad flat no-lead package, or a dual flat no-lead package. In this or other packages, the mounting substrate may be a die pad and/or may provide thermal and electrical contact between circuitry on the semiconductor die and a ground plane on a printed circuit board on which the package is mounted. Alternatively, a thermally conductive substrate, such as a copper or copper-based substrate, may be used in this or other packages.

Alternatively, the molded air cavity package may be a land grid array package, wherein the mounting substrate comprises a printed circuit board, wherein the package contacts each comprise a respective land formed on an outer surface of the printed circuit board. In this case, the package contacts each further comprise a pad formed on an inner surface of the printed circuit board, the pad forming a respective package contact terminal. The semiconductor die may be flip-chip mounted to the printed circuit board using the pads formed on the inner surface of the printed circuit board. Alternatively, the molded air cavity package further comprises bond wires for connecting the package contact terminals to the semiconductor die.

Each of the second lid support elements may extend toward and abut a respective first lid support element to collectively form a respective column. In this embodiment, the first and second lid support elements are both cylindrical.

Alternatively, each of the second cover support elements may comprise a recess in which the corresponding first cover support element is received.

For example, the plurality of second cover supporting members includes at least three second cover supporting members, wherein the shape of the recess of two of the at least three second cover supporting members restricts relative movement between the cover and the main body to mutually different directions parallel to the mounting substrate during arrangement of the cover on the main body. For example, the recess of the second cover support element comprises one of a groove and an elongated slot. The remaining second cover supporting members need not have a function of restricting relative movement.

Alternatively, the plurality of second lid support elements comprises at least three second lid support elements, wherein the recesses of two of the at least three second lid support elements have a shape complementary to the shape of the respective first lid support elements such that: relative movement between the cover and body in all directions parallel to the mounting substrate is limited during placement of the cover on the body.

The upper surface of the upper portion may comprise one or more first alignment structures and the lower surface of the lid side wall may comprise one or more second alignment structures, wherein the first and second alignment structures are configured to cooperate during the disposition of the lid on the body to cause the lid and the body to move relative to each other to a position in which the first and second lid support elements abut each other. The one or more first and second alignment structures may be configured to perform a coarse alignment during which there is physical contact between the first and second alignment structures. Thereafter, the cover and the body may be moved relative to each other to bring the cover and the body into the position as described below: in which position the first and second cover support elements are aligned and abut each other, and in which position the first and second alignment structures are no longer in direct physical contact. The first and second alignment structures may at least partially form walls of the channel. For example, the first alignment structure may comprise a recess in the upper surface of the upper portion and the second alignment structure may comprise a corresponding protrusion extending towards the recess in the upper surface of the upper portion, or vice versa. Additionally or alternatively, the first and second alignment structures may include mating angled surfaces that extend upward and outward relative to the center of the package and the lower surface of the thermally conductive substrate.

The mounting substrate may comprise a thermally conductive substrate. In the latter case, the semiconductor may comprise an electrically conductive silicon substrate on which a laterally diffused metal oxide semiconductor "LDMOS" transistor is disposed, and the grounding of the LDMOS transistor is achieved through the silicon substrate and the thermally conductive substrate. Alternatively, the semiconductor may comprise an insulating gallium nitride substrate on which a field effect transistor "FET" is arranged, and the grounding of the FET is achieved through a via in the gallium nitride substrate and the thermally conductive substrate. The LDMOS transistor or FET may form part of a Doherty amplifier. Here, it should be noted that the insulated gallium nitride substrate also includes an insulated gallium nitride epitaxial layer grown on an insulating substrate such as silicon, silicon carbide, or sapphire.

Furthermore, the present invention is not limited to a single semiconductor die. Instead, multiple semiconductor dies may be mounted on the same or different thermally conductive substrates or die pads.

According to another aspect, the invention provides an electronic device comprising a molded air cavity package as defined above. Such devices may include base stations or base station transmitters for mobile communications, or solid state cooking devices.

Drawings

The invention will be described in more detail below with reference to the accompanying drawings, in which:

FIG. 1 shows the general structure of a molded air cavity package;

FIGS. 2A and 2B show general top and side views, respectively, of the package of FIG. 1;

FIGS. 3A and 3B show two respective cross-sectional views of an embodiment of a molded air cavity package according to the present invention;

figures 4A to 4D show different possibilities of arranging the cylinders according to the invention;

FIG. 5 shows a first detailed embodiment of a molded air cavity package according to the present invention;

FIG. 6 shows a second detailed embodiment of a molded air cavity package according to the present invention;

FIG. 7 shows a third detailed embodiment of a molded air cavity package according to the present invention;

FIG. 8 shows a fourth detailed embodiment of a molded air cavity package according to the present invention;

FIGS. 9A-9C illustrate a detailed embodiment of a molded air cavity package of the QFN, PQFN or DFN type in accordance with the present invention; and

figures 10A and 10B show a detailed embodiment of a molded air cavity package according to the present invention which is of the LGA type.

Detailed Description

Figures 3A and 3B show two respective cross-sectional views of an embodiment of a molded air cavity package according to the present invention. More specifically, fig. 3A shows a sectional view at the position of the lead 3. In contrast to the general structure of fig. 1, the embodiment in fig. 3A includes posts 100 disposed in the corners of the package. The column is shown in fig. 3B.

Fig. 3B shows a cross-sectional view at the location of the post 100. As shown, the post 100 extends downward from the cover base 8A and abuts the support surface 6. The support surface 6 in fig. 3B is coplanar with the upper surface of the lead terminal 3A in fig. 3A.

In the embodiment shown in fig. 3B, the first lid support element is formed by a cylindrical protrusion, while the second lid support element is formed by a flat portion of the support surface 6.

Although fig. 3A and 3B show a single post 100, it should be noted that the present invention is particularly directed to embodiments having four posts, each disposed in a respective corner of the package. However, the invention is not limited to four posts, as embodiments with more or fewer (e.g., three) posts are equally possible.

Fig. 4A to 4D show different possibilities of arranging the cylinders according to the invention, but this does not exclude other possibilities of the application. In these embodiments, the first lid support member 100 having a columnar shape extends downward from the lid base 8. The first cover supporting member 100 may have any shape, and may be implemented as a cylinder or a bar-shaped body. Furthermore, the downwardly facing end of the first lid support element 100 may be tapered, rounded and/or chamfered.

The embodiment shown in fig. 4A includes four first cover support elements 100, each first cover support element 100 being disposed in a respective corner of the cover base 8A and offset relative to the cover sidewall 8B. The support surface 6 of the upper part 4 comprises four recesses 201, 202 in which the first lid support element 100 is received. As shown in fig. 4A, the recess 201 has an elongated shape, and the movement of the first cover support member 100 in the recess is limited in one dimension. For example, the recess 201 shown in the upper left corner restricts the movement of the first cover support element 100 to a different direction than the recess 201 shown in the lower right corner. The shape of the recess 201 along two different cut lines (i.e., line I and line II) is shown at the bottom of fig. 4A.

The recess restricts the movement of the cover 8 in two orthogonal directions (both of which are parallel to the lower surface 1A of the heat conductive substrate 1), and the alignment of the cover 8 with respect to the main body is achieved by the recess 201. The recess 202 need not have a very strong limiting effect on the mutual movement between the body and the cover 8. However, the abutment between the first cover support element 100 and the recesses 201, 202 determines how the cover 8 is positioned relative to the body in a direction perpendicular to the lower surface 1A of the heat conductive substrate 1.

Fig. 4D shows an alternative to fig. 4A, wherein one elongated recess 202 is replaced by a recess 203 having a shape complementary to the shape of the first lid support element 100. For example, the shape and size of the recess 203 may be similar to the shape and size of the first lid support element 100 to achieve a tight fit. Other recesses 202 may have a looser fit.

Fig. 4B shows a different embodiment, wherein the shape of the two recesses 203 is complementary in shape and size to the shape of the first lid support element 100. The recess 202 has a much wider shape and does not or not much relate to the alignment of the cover 8 with respect to the body in a direction parallel to the lower surface 1A.

Fig. 4C shows that the second lid support element takes the form of a groove shaped as a V-groove, in which the first lid support element 100 is received. The grooves of the directly opposing second cover support members 204 are aligned. Centerlines L1, L2 through directly opposing second lid support elements 204 preferably intersect at a central location C in the package.

Figure 5 shows a cross-sectional view of a first detailed embodiment of a molded air cavity package according to the present invention taken at a corner of the package. As shown in the detailed view of the bottom, the first lid support element 100 is cylindrical, is integrally connected with the lid base 8A, and abuts against the flat portion of the support surface 6. Furthermore, the lower surface 9 and the upper surface 10 are provided with alignment structures. More specifically, the lower surface 9 includes a recess 9A, and the upper surface 10 includes a protrusion 10A extending partially into the recess 9A. The upper surface 10 and the lower surface 9 together define a channel 12 in which an adhesive (not shown) for fixedly attaching the cover 8 to the body is disposed. As shown, the channel 12 is wider in the direction from the cavity to the outside of the package. Thus, the liquid adhesive in the channel 12 will tend to flow in an outward direction because the flow resistance of such flow is less than in an inward direction. Thus, the risk of liquid adhesive flowing into the cavity is reduced.

As shown, when the cover 8 is properly aligned, the recess 9A and the protrusion 10A do not come into physical contact. However, during the initial stage of aligning the cover 8, when the adhesive has not spread completely over the channel 12, the recess 9A and the protrusion 10A may be in physical contact for path alignment.

Fig. 6 to 8 show different embodiments which, when compared to fig. 5, differ in the way the first and second cover support elements are realized. In fig. 6, the support surface 6 includes a post 100 extending toward the lid base 8A. More specifically, the post 100 abuts a flat portion of the lid base 8A, the flat portion of the lid base 8A forming the second lid support element. On the other hand, in fig. 7, the post 100A extends from the cover base 8A, and the support surface 6 includes a post 100B extending toward the post 100A. When properly aligned, the protrusions 100A, 100B form a single post.

Although fig. 5-8 illustrate an embodiment in which the lower surface 9 of the lid sidewall 8B includes a recess 9A and the upper surface 10 of the upper portion 4 includes a protrusion 10A, it should be understood that different shapes of channel defining structures are equally possible, such as the parallel surfaces shown in fig. 1. Furthermore, the invention relates equally to embodiments in which the upper surface 10 has a recess and the lower surface 9 has a protrusion.

Fig. 9A-9C illustrate a detailed embodiment of a molded air cavity package of QFN, PQFN or DFN type according to the present invention. In this case, the die pad 1 may serve as a mounting substrate on which the semiconductor die 2 is mounted. The die pad 1 is fixedly connected to the signal pad 3 by the cured molding compound 4A. The sectional view shown in fig. 9A is at a position where the signal pad 3 is present, and the sectional view shown in fig. 9B is at a position where the signal pad 3 is absent.

A distinction can again be made between an inner region 4A and an outer region 4B of the lower part 4 of the body, wherein the outer region 4B is fixedly connected to the upper part 5.

Fig. 9C shows a sectional view at the position of the post 100 formed in the cap base 8A. The post 100 abuts the upper surface of the inner region 4A.

Figures 10A and 10B show a detailed embodiment of a molded air cavity package according to the present invention which is of the LGA type. In the present embodiment, the mounting substrate is formed of a printed circuit board 1, and a plurality of lands (lands) are formed on an outer surface of the printed circuit board 1 for mounting the package on, for example, another printed circuit board. In fig. 10A, a single pad 3 connected to a pad 3A on the inner surface of the printed circuit board 1 is shown. The pad 3 and the pad 3A are connected using a via 3B. Bond wires 7 are used to electrically connect each of the pads 3 to circuitry on the semiconductor die 2. It should be understood that the package may comprise more solder pads 3 formed on the outer surface of the printed circuit board. Furthermore, the printed circuit board 1 may comprise a metal sheet (coin) or other thermally conductive material inside the printed circuit board to improve the thermal contact between the semiconductor 2 and another printed circuit board on which the package is mounted.

Fig. 10B shows a cross-sectional view at the location of the post 100. As shown, the post 100 is supported on the upper surface of the inner region 4A of the lower portion 4. Embodiments are also possible in which the posts 100 are supported on the upper surface of the printed circuit board 1.

It should be noted that embodiments are also possible in which the semiconductor 100 is flip-chip mounted on the printed circuit board 1 instead of using the bonding wires 7.

For example, at least some of the above advantages may be equally obtained when using a closed perimeter rather than spaced apart columns formed by the first and second lid support elements. However, the periphery may also have a plurality of adjacently disposed and integrally connected posts.

A molded air cavity package in which closed perimeters are used instead of spaced-apart posts, which air cavity package may be configured in the manner defined in the preamble of claim 1, and may be further characterized in that the molded air cavity package comprises a first cover support element formed in one of the interior area and the cover base and a second cover support element formed in the other of the interior area and the cover base, wherein the first cover support element extends towards and abuts the second cover support element forming a closed perimeter spaced from the upper portion and cover sidewalls.

Other advantageous embodiments related to the spaced apart posts described in the dependent claims may be modified to include a closed perimeter. For example, the second lid support element may comprise a recess in which the first lid support element is received. The recess of the second lid support element may comprise an annular groove. The annular groove has a generally rectangular shape and may be complementary to the shape of the first lid support element.

Having a closed perimeter provides an additional barrier to adhesive flow inward. In addition, having an annular groove can help properly align the cap relative to the body formed of the cured molding compound.

In the foregoing, the invention has been explained using detailed embodiments thereof. However, the present invention is not limited to these examples. Rather, various modifications to these embodiments are possible without departing from the scope of the invention, which is defined by the appended claims and their equivalents.