Lead frame for packaging of semiconductor devices, semiconductor device and process for manufacturing a semiconductor device

Abstract

Embodiments of the present disclosure relate to a leadframe for packaging of a semiconductor device, a semiconductor device, and a process for manufacturing a semiconductor device. A leadframe for an integrated electronic device includes a die pad made of a first metal material. A top coating formed of a second metal material is disposed on a top surface of the die pad. The second metal material has a lower oxidation rate compared to the first metal material. The top coating leaves a plurality of corner portions of the top surface of the die pad exposed. Subsequent heating operations, for example associated with wire bonding, cause an oxide layer to form at locations on the corner portions of the top surface of the die pad that are in contact with the top coating.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Italian patent application No. 102019000013704, filed on August 1, 2019, the contents of which are incorporated herein by reference in their entirety to the fullest extent permitted by law. Technical Field

[0003] This invention relates to a lead frame for packaging a semiconductor device, as well as a semiconductor device and a process for manufacturing the semiconductor device. Background Technology

[0004] As is well known, semiconductor devices (such as integrated circuits and MEMS devices) are encapsulated in corresponding packages that perform the functions of protection and interface with the outside world. For example, packages that enable so-called "surface mounting" on printed circuit boards are known.

[0005] More specifically, surface mount packages include, for example, the so-called "quadrilateral flat no-lead" (QFN) type of package, also known as "micro leadframe" (MLF) package or "small outline no-lead" (SON) package.

[0006] Typically, a QFN package includes an area encapsulated or embedded in resin, which is a metal lead frame (usually made of copper) that forms at least one terminal array distributed on the bottom surface of the package.

[0007] like Figure 1 and 2 As shown, the leadframe 1 includes a body 2, which is planar and has a polygonal shape (typically a square or rectangle) in a top view; the body 2 defines a top surface 6a and a bottom surface 6b. A plurality of pads 8 extend upward from the body 2 (i.e., from the top surface 6a). Additionally, the leadframe 1 includes so-called die pads 10, which extend upward from the body 2 and are surrounded by the inner pads 8 at a distance.

[0008] The main body 2, pad 8, and die pad 10 form a single metal component. Furthermore, the die pad 10 is planar and has a polygonal shape (typically a square or rectangle) in a top view. Figure 1 In the middle, the bare die pad 10 has a parallelepiped shape, and its sidewalls 16 intersect at the four edges 11 (in Figure 1 Only three are visible in the middle.

[0009] Additionally, the leadframe 1 is typically electroplated using silver or a metallic alloy (such as NiPdAu). Specifically, the leadframe 1 undergoes a plating process (e.g., electroplating) that allows the formation of a top coating region 12 and a plurality of secondary coating regions 14 on the die pad 10, each of the secondary coating regions 14 being disposed on a corresponding pad 8. As previously mentioned, the top coating region 12 and the secondary coating region 14 are formed of silver or a metallic alloy, for example, of a material less prone to oxidation (especially in air) compared to the material forming the leadframe 1 (i.e., of a material having a lower oxidation rate than the leadframe). Furthermore, the top coating region 12 and the secondary coating region 14 may have thicknesses ranging from 3 to 9 μm; the pad 8 and the die pad 10 may have thicknesses ranging from 3 to 4 μm.

[0010] Traditionally, the leadframe is manufactured as a strip and then used in the manufacturing process. Furthermore, the manufacturing process typically includes an etch-back step to remove the body 2 and separate the pads 8 from the die pads 10.

[0011] Additionally, the manufacturing process typically includes the following steps: placing a bare die (not shown) on the die pad 10, and then electrically connecting the conductive pads of the die to the corresponding pads 8 of the lead frame 1 by means of wire bonding 24, such as... Figure 3 As shown. To establish wire bonding 24, a heat treatment is typically performed in air at a temperature of approximately 200°C for about ten minutes; this heat treatment results in controlled oxidation of the exposed portions of the lead frame 1 (i.e., portions of the lead frame 1 not coated by the top coating region 12 or not coated by the secondary coating region 14). Therefore, after the heat treatment, an oxide layer 27 extends on and below portions of the lead frame 1.

[0012] Then, encapsulation region 25 is typically formed on top of lead frame 1 and die by molding. Encapsulation region 25 (also referred to as "molding material") may be made of thermosetting epoxy resin and extends in direct contact with portions of top coating region 12, secondary coating region 14, and oxide layer 27.

[0013] according to Figure 4In the various examples shown, the lead frame 1 may include: a die pad structure 28 including a die pad 10; a ground ring 29 laterally surrounding the die pad 10; and a trench T0 extending between the die pad 10 and the ground ring 29 to expose a corresponding portion of the underlying body 2. The ground ring 29 extends upward from the body 2, has the same thickness as the die pad 10, and has a square frame shape; the ground ring 29 forms a single piece with the body 2, the die pad 10, and the pad 8. The pad 8 surrounds the die pad structure 28. Additionally, the ground ring 29 is coated on top by an additional coating region 12', which is made of the same material as the top coating region 12 and has the same thickness as the latter.

[0014] Figure 1 and Figure 4 The projection of the outline OT, i.e. the bare sheet that may be on the top coating area 12, is shown in dashed lines.

[0015] As already mentioned, the difference in the coefficient of thermal expansion (CTE) between package region 25 and lead frame 1 can cause mechanical stress due to temperature changes that occur during the operation of electronic devices implemented in the die.

[0016] Specifically, refer to Figure 1 and 2 As an example, note that mechanical stresses are concentrated at the corners of the die pads 10, which, in particular, can cause local delamination (i.e., separation of a portion of the top coating region 12 from the package region 25) when the die is exposed to the outside atmosphere. This local delamination can then propagate, causing cracks over time and affecting device reliability.

[0017] Several solutions have been proposed to address the layering problem.

[0018] Specifically, the first solution envisioned using an additional adhesion promoter applied to the lead frame surface. Unfortunately, this solution would be very expensive.

[0019] The second solution envisions forming retention structures (such as grooves or recesses) within the leadframe. However, this solution has proven ineffective not only because it requires reducing the available package space, but also because it is not suitable for larger package formats that generate higher stress.

[0020] Finally, a third solution was proposed, which envisions using so-called roughened leadframes (i.e., leadframes that have undergone chemical or mechanical processes) to roughen their surfaces. Unfortunately, this solution also incurs high costs; furthermore, it adversely affects the control of die attachment adhesive and the reliability of wire bonding due to increased substrate wettability.

[0021] There is a need in the art for a lead frame for semiconductor devices that would at least partially address the aforementioned drawbacks. Summary of the Invention

[0022] According to the present invention, a lead frame for a semiconductor device, a semiconductor device, and a process for manufacturing a semiconductor device are provided.

[0023] In one embodiment, a lead frame for integrating electronic devices includes: a bare pad structure made of a first metallic material, the bare pad structure including bare pads and defined by a top structure surface; and a top coating structure formed of a second metallic material and disposed on the top structure surface, the second material having a lower oxidation rate compared to the first material; wherein the top coating structure exposes a plurality of corners of the top structure surface.

[0024] In one embodiment, an integrated electronic device includes: a lead frame as described above; a plurality of oxide regions, each oxide region coating a corresponding corner of a top structure surface and laterally contacting a top coating structure; a die disposed on a die pad; and a dielectric package region covering the die, the oxide regions, and portions of the top coating structure adjacent to the oxide regions in direct contact.

[0025] In one embodiment, a method for manufacturing an integrated electronic device includes: attaching a die to a lead frame as described above; establishing a wire bond between the die and the lead frame, the establishment of the wire bond including performing a heat treatment that results in the formation of a plurality of oxide regions, each oxide region coating a corresponding corner of a top structure surface and laterally contacting a top coating structure; and then forming a dielectric package region such that it directly contacts the die, the oxide regions, and portions of the top coating structure adjacent to the oxide regions. Attached Figure Description

[0026] To better understand the invention, preferred embodiments will now be described by way of non-limiting example only with reference to the accompanying drawings, wherein:

[0027] Figure 1 A perspective view of the lead frame is shown schematically.

[0028] Figure 2 schematically shown Figure 1 The lead frame shown is along Figure 1 The cross-section cut by line II-II shown;

[0029] Figure 3 Schematic illustration including Figure 1 and 2 A cross-section of a portion of the leadframe package device shown;

[0030] Figure 4 A perspective view of another lead frame is shown schematically;

[0031] Figure 5 A perspective view of this lead frame is shown schematically;

[0032] Figure 6 schematically shown Figure 5 The lead frame shown is along Figure 5 The cross section cut by line VI-VI shown;

[0033] Figure 7 The schematic diagram illustrates the steps included during the manufacturing process. Figure 5 and 6 A cross-section of a portion of the leadframe package device shown;

[0034] Figure 8 This schematically illustrates the subsequent steps in the manufacturing process. Figure 7 The cross-section of the packaged device shown;

[0035] Figure 9 A perspective view schematically illustrating a variation of this lead frame is shown.

[0036] Figure 10 A perspective view schematically illustrating another variation of this lead frame is shown.

[0037] Figure 11 schematically shown Figure 10 An enlarged perspective view of a portion of the lead frame shown;

[0038] Figure 12 schematically showing from Figure 10 and 11 Enlarged perspective view of the bottom section of a portion of the lead frame shown;

[0039] Figure 13 The schematic diagram illustrates the components under normal operating conditions, including Figures 10 to 12 The cross-section of the lead frame packaged device is shown; and

[0040] Figure 14 Schematic illustration of when stratification occurs Figure 13 The cross-section of the packaged device is shown. Detailed Implementation

[0041] As described below, refer to Figure 1 The leadframe shown (which does not imply any limitation) is based on the idea of ​​exposing the corners of the die pad structure to create sacrificial oxide regions that allow for confined delamination. Therefore, the following description will be limited to... Figure 1 The differences are shown compared to lead frame 1; in addition, unless otherwise stated, the same reference numerals will be used.

[0042] In detail, Figure 5 and 6 The lead frame (designated here by 101) is shown, wherein the die pads (designated here by 110) have a... Figure 1 and 2 The bare pad 110 has the same shape as the die pad 10. In addition, the die pad 110 is defined on top by the front surface 103. The top coating area (designated here by 112) extends on the front surface 103.

[0043] More specifically, the top coating area 112 exposes the four corners 117 of the bare die pad 110, which are defined at the top by corresponding portions of the front surface 103, hereinafter referred to as the corner surface portions 117S.

[0044] Specifically, each corner 117 includes a corresponding edge (designated here by 111) where two adjacent sides of the die pad 110 intersect, the edge being perpendicular to and contacting the front surface 103. Additionally, the four corners 117 have one and the same shape, but this does not imply any limitation; specifically, in the top view, the corners 117 have a square shape. Each apex surface portion 117S extends from its corresponding edge 111 and is separate from the other apex surface portions 117S; in the top view, each apex surface portion 117S extends from the corresponding vertex of the polygonal shape defined by the top coating region 112.

[0045] like Figure 7 As shown, during the manufacturing process, particularly during wire bonding, the corresponding heat treatment results in the formation of a bottom oxide layer 126 and a top oxide layer 127, the bottom oxide layer 126 extending below the bottom surface 6b. As an example, the bottom oxide layer 126 and the top oxide layer 127 may have thicknesses ranging from 100 nm to 200 nm.

[0046] The top oxide layer 127 includes a main portion 128 that extends on the top surface 6a of the body 2 and on the sidewalls of the pads 8 and the die pads 110; thus, the main portion 128 of the top oxide layer 127 coats the edges 111 of the die pads 110. Additionally, the top oxide layer 127 includes four additional portions 129 (in... Figure 7 Only one is visible in the text, referred to below as the sacrifice portion.

[0047] Specifically, each sacrificial portion 129 extends on the corresponding corner 117 of the bare pad 110 (i.e., on the corresponding top corner surface portion 117S). In addition, each sacrificial portion 129 is laterally staggered relative to the top coating region 112 it directly contacts, thereby forming a corresponding interface IF.

[0048] As an example, refer to the following manufacturing steps for forming the package region 25 (e.g.) Figure 8 As shown), this step itself is known, including mold curing at 170°C (as an example). The encapsulation region 25 also extends particularly over the sacrificial portion 129.

[0049] For the following reasons, the mechanical stress caused by the above curing step due to CTE (coefficient of thermal expansion) mismatch is unlikely to cause delamination between the sacrificial portion 129 and the encapsulation region 25.

[0050] Specifically, it should be noted that the adhesion between the top oxide layer 127 and the package region 25 is greater than the adhesion between the top oxide layer 127 and the lead frame 101. More specifically, at each corner of the die pad 110, the adhesion between the corresponding sacrificial portion 129 and the overlying portion of the package region 25 is greater than the adhesion between the sacrificial portion 129 and the lower corner 117 of the die pad 110. Therefore, delamination may occur at most between the sacrificial portion 129 and the die pad 110; furthermore, this delamination does not propagate beyond the interface IF between each sacrificial portion 129 and the top coated region 112, and therefore does not affect the adhesion between the package region 25 and the top coated region 112. Thus, the package region 25 and the top coated region 112 continue to encapsulate the die without exposing the latter to external air. The reduced size of the corner surface portion 117S relative to the top coated region 112 contributes to this result.

[0051] Figure 9 Another embodiment is shown, which will be referred to below. Figure 4 The differences in the lead frame shown are described.

[0052] In detail, referring to the additional front surface 103' to indicate the front surface of the grounding ring 29, the additional coating area 12' exposes the four corners 217 of the grounding ring 29, which are defined at the top by the corresponding portion of the additional front surface 103, hereinafter referred to as the additional apex corner surface portion 217S.

[0053] Specifically, each corner 217 of the grounding ring 29 includes a corresponding edge 211 of the lateral outer surface of the square frame forming the grounding ring 29. Furthermore, in the top view, each corner surface portion 217S has an "L" shape.

[0054] During the manufacturing process, each additional apex surface portion 217S is coated with a corresponding oxide sacrificial region (not shown). Therefore, Figure 9 The embodiments shown guarantee compatibility with Figures 6 to 8 The illustrated embodiments have the same advantages.

[0055] Figures 10 to 12 Another embodiment is shown, in which the lead frame (designated here by 301) is adapted to form a package of the so-called Thin Quad Flat Package (TQFP) type.

[0056] In this configuration, the lead frame 301 includes a bare die pad 310 with a square planar shape, which is accessed from the top and bottom by 303 (in...) Figure 11 The front and rear surfaces 405 (as shown in the image) are defined. The top coated area (as specified here by 312) exposes the four corner surface portions (as specified here by 317S). The edges of the die pad 310 (as specified here by 311) are beveled, but this does not imply any limitation. Each edge 311 is still formed by the corresponding pair of adjacent sidewalls of the die pad 310 (as specified here by 316).

[0057] Additionally, the rear surface 405 is coated with a bottom coating region 412, which is formed of the same material as the top coating region 312 (e.g., silver), and exposes the four corners 417S of the rear surface 405 (hereinafter referred to as bottom corner surface portions 417S).

[0058] Pairs (optional) of trenches with concentric square rings may exist, but this does not imply any limitations. Specifically, the first trench T1 and the second trench T2 may extend through a portion of the bottom coating region 412 and the die pad 310, and they have rectangular cross-sections. More specifically, the second trench T2 surrounds the first trench T1 at a distance; furthermore, the first trench T1 and the second trench T2 do not completely cross the die pad 310 (i.e., they are blind trenches) and extend in such a manner as: Figure 12 As shown, each bottom corner surface portion 417S is divided into first, second, and third exposed sub-portions 418A, 418B, and 418C. A first groove T1 extends between the first and second exposed sub-portions 418A and 418B in the bottom view, and a second groove T2 extends between the second and third exposed sub-portions 418B and 418C. Therefore, the first exposed sub-portion 418A is arranged inwards, while the third exposed sub-portion 418C is arranged outwards towards its corresponding edge 311; the second exposed sub-portion 418B is inserted between the first exposed sub-portion 418A and the third exposed sub-portion 418C.

[0059] Additionally, the lead frame 301 includes an inner frame 450, which is square and planar, and surrounds the die pad 310 at a distance, connected to the die pad 310 by means of a plurality of bridges 451. Specifically, the die pad 310, the bridges 451, and the inner frame 450 form a single metal piece (i.e., they are made of the same material); furthermore, the inner frame 450 can be vertically staggered relative to the die pad 310, i.e., it can be arranged at a higher height than the die pad 310 (measured in a direction perpendicular to the die pad 310). Additionally, the inner frame 450 is defined at its top and bottom by a top frame surface 452 and a bottom frame surface 453, respectively.

[0060] The top coating area 312 also extends on the front surface of the bridge 451 and on the top frame surface 452, exposing the four corners 457S of the latter (hereinafter referred to as top frame surface portions 457S). In a top view, each top frame surface portion 457S has an "L" shape, with its concave surface accommodating a portion of the corresponding apex corner surface portion 317S.

[0061] Additionally, the bottom coating region 412 also extends on the rear surface of the bridge 451 and on the bottom frame surface 453, exposing the four corners 467S of the latter (hereinafter referred to as bottom frame surface portions 467S). In a bottom view, each bottom frame surface portion 467S has an "L" shape, with its concave surface accommodating the corresponding third exposed sub-portion 418C. Each bottom frame surface portion 467S and the corresponding top frame surface portion 457S define the corresponding corners 499 of the inner frame 450 at the top and bottom, respectively.

[0062] The lead frame 301 further includes an outer frame 470, which is planar and square, and surrounds the inner frame 450 and a plurality of cantilever leads 472 at a distance. Each cantilever lead 472 is attached to the outer frame 470 and extends toward the inner frame 450. The outer frame 470 may be vertically staggered relative to the inner frame 450, but this does not imply any limitation, and in particular, it may be arranged at a higher height than the inner frame 450. In this case, the die pads 310, the inner frame 450, and the outer frame 470 are located in corresponding planes, and although they are arranged at different heights, they are parallel.

[0063] Additionally, lead frame 301 includes four connecting elements 474, hereinafter referred to as connectors 474. Each connector 474 has an elongated shape and two ends, a first end fixed to the inner frame 450 and a second end fixed to the outer frame 470. The die pad 310, inner frame 450, outer frame 470, cantilever lead 472, and connectors 474 form a single metal component.

[0064] Each connecting rod 474 is defined at its top and bottom by a corresponding top surface 493 and a corresponding bottom surface 495, respectively. Furthermore, each connecting rod 474 includes a sloped portion 475A and a flat portion 475B. The flat portion 475B is connected to the outer frame 470. The sloped portion 475A is inserted between the inner frame 450 and the flat portion 475B; specifically, the sloped portion 475A is connected to a corresponding corner 499 of the inner frame 450. Additionally, either the top surface 493 or the bottom surface 495 has the shape of a pair of interconnected flat surfaces (i.e., a sloped flat surface and a horizontal flat surface interconnected).

[0065] Additionally, the upper sides of the cantilever lead 472 and the outer frame 470 are coated with an outer top coating region 512; the lower sides of the cantilever lead 472 and the outer frame 470 are coated with an outer bottom coating region 613. The outer top coating region 512 and the outer bottom coating region 613 may be formed of the same metallic material as the top coating region 312 and the bottom coating region 412.

[0066] The outer top coating area 512 exposes a portion 517S of the top surface 493 of each connecting rod 474, hereinafter referred to as the exposed top elongated surface 517S. Each exposed top elongated surface 517S is connected to a corresponding top frame surface portion 457S.

[0067] The outer bottom coating area 613 exposes a portion 617S of the top surface 493 of each connecting rod 474, hereinafter referred to as the exposed bottom elongated surface 617S. Each exposed bottom elongated surface 617S is connected to a corresponding bottom frame surface portion 467S.

[0068] like Figure 13 As shown, leadframe 301 can be used to manufacture integrated electronic device 700, which includes a die 502 that is secured to a portion of the top coated area 312 covering the die pads 310 by means of an insert layer 503 of epoxy conductive adhesive (filled with silver). Package area 25 encloses leadframe 301 that has previously undergone a dicing process, which results in the removal of outer frame 470 and portions of cantilever leads 472 and connectors 474 connected to the outer frame in a manner known per se.

[0069] Encapsulation region 25 exposes the bottom coating region 412 and portions of each connector 474. Specifically, for each connector 474, the exterior of the exposed top elongated surface 517S and the exposed bottom elongated surface 617S extends outside of encapsulation region 25; the interior of the exposed top elongated surface 517S and the exposed bottom elongated surface 617S extends within encapsulation region 25.

[0070] Additionally, the portion of the connecting rod 474 covered on the opposite side by the outer top coating region 512 and the outer bottom coating region 613 extends outside the encapsulation region 25.

[0071] As previously explained, the exposed portion of the lead frame 301 is covered with a metal oxide layer. Specifically, each exposed top elongated surface 517S and the corresponding top frame surface portion 457S are coated with a corresponding top oxide region 800; each exposed bottom elongated surface 617S and the corresponding bottom frame surface portion 467S are coated with a bottom oxide region 802, thereby forming a single oxide region having a top oxide region 800.

[0072] It is important to note that delamination is more likely to occur between the top / bottom oxide regions 800 / 802 and the lead frame 301 compared to the delamination between the top / bottom oxide regions 800 / 802 and the package region 25. As an example, Figure 14 The delamination that occurs between the top oxide region 800 and the lead frame 301 is shown, and this delamination only propagates to the interface between the top oxide region 800 and the top coating region 312 (as still specified by IF), without affecting the adhesion between the top coating region 312 and the die pad 310.

[0073] More specifically, the interface IF between the top oxide region 800 and the portion of the top coating region 312 adjacent to (i.e., in direct contact with) the top oxide region 800 is covered by the encapsulation region 25 and acts as a stopping point for the delamination propagation between the top oxide region 800 and the lead frame 301. Therefore, by way of example, this delamination does not cause the encapsulation region 25 to separate from the top coating region 312.

[0074] Based on the previously described and illustrated content, the advantages offered by this solution are clearly evident.

[0075] In particular, this leadframe represents a cost-effective solution that allows for reduced delamination between the molded package area and the metal-coated area of ​​the leadframe in packaged integrated electronics.

[0076] In summary, it is evident that modifications and variations can be made to the description and illustrations herein without departing from the scope of the invention as defined by the appended claims.

[0077] For example, the lead frame can have a different shape than the shape previously shown.

Claims

1. A lead frame for integrating electronic devices, comprising: The bare die pad is made of a first metallic material, and the bare die pad includes a top surface; A top coating, made of a second metallic material, is arranged to contact the top surface, wherein the second metallic material has a lower oxidation rate than the first metallic material. An oxide coating covers the top surface of the bare die pad at the corners not covered by the top coating. The top coating covers the entire top surface except for the corners of the top surface of the bare die pads, which are not covered by the top coating and are separated from each other. The oxide coating is in lateral contact with the top coating.

2. The lead frame according to claim 1, wherein the die pad includes a plurality of edges at the location where the sides of the die pad intersect; and wherein each edge is transversely cut to the corresponding corner in direct contact with it.

3. The lead frame according to claim 1, wherein each corner has a square shape.

4. The lead frame according to claim 1, wherein the die pad is supported by a body, and wherein the die pad and the body form a single piece.

5. The lead frame according to claim 1, further comprising: A grounding ring laterally surrounds the bare die pad, and the grounding ring includes a top surface, wherein the grounding ring has the shape of a square frame; as well as An additional top coating, made of the second metallic material, is arranged to contact the top surface of the grounding ring; and The corners of the top surface of the grounding ring are not covered by the additional top coating.

6. The lead frame according to claim 5, wherein the die pad and the grounding ring are supported by a body, and wherein the die pad, the grounding ring and the body form a single piece.

7. The lead frame of claim 5, further comprising an oxide coating covering the top surface of the die pad at the corner not covered by the top coating, and covering the top surface of the grounding ring at the corner not covered by the additional top coating, wherein the oxide coating is in lateral contact with the top coating and in lateral contact with the additional top coating.

8. The lead frame of claim 1, further comprising a plurality of pads having a top surface coated with a coating region made of the second metallic material.

9. The lead frame of claim 8, wherein the die pads and the plurality of pads are supported by a body, and wherein the die pads, the plurality of pads and the body form a single piece.

10. The lead frame according to claim 1, further comprising: An inner frame that laterally surrounds the bare die pads; An outer frame that laterally surrounds the inner frame; Multiple connecting rods are inserted between the outer frame and the inner frame; as well as Another top coating, made of the second metallic material, is arranged to contact the top surfaces of the inner frame and the outer frame; The portion of the inner frame at the location where the inner frame connects to the connecting rod is not covered by the other top coating.

11. The lead frame of claim 10, wherein the top surface of the connector is not covered by the other top coating.

12. The lead frame of claim 10, wherein the inner frame and the outer frame have different heights, and wherein each connector includes a corresponding tilt portion to transition between the different heights.

13. The lead frame according to claim 10, further comprising: A bottom coating structure extends below the bare die pads and the inner frame; as well as The outer bottom coating area extends below the outer frame; and The bottom surface of the inner frame at the location where the inner frame connects to the connecting rod is not covered by the outer bottom coating area.

14. The lead frame of claim 10, further comprising an oxide coating covering the top surface of the bare die pad at the corner not covered by the top coating, and covering the portion of the inner frame not covered by the other top coating, wherein the oxide coating is in lateral contact with the top coating and in lateral contact with the other top coating.

15. An integrated electronic device, comprising: Lead frame, including: A bare die pad, made of a first metallic material, and the bare die pad includes a top surface; and A top coating, made of a second metallic material, is arranged to contact the top surface, wherein the second metallic material has a lower oxidation rate than the first metallic material; The top coating covers the entire top surface except for the corners of the top surface of the bare die pads, which are not covered by the top coating and are separated from each other; The oxidized area is coated at the corner and makes lateral contact with the top coating; An integrated circuit die, supported by said die pads; and The dielectric packaging area covers the bare die, the oxidized area, and the top coating adjacent to the oxidized area in direct contact.

16. The integrated electronic device of claim 15, wherein each corner has a square shape.

17. The integrated electronic device of claim 15, further comprising: A grounding ring laterally surrounds the bare die pad, and the grounding ring includes a top surface, wherein the grounding ring has the shape of a square frame; as well as An additional top coating, made of the second metallic material, is arranged to contact the top surface of the grounding ring; and The corners of the top surface of the grounding ring are not covered by the additional top coating; as well as The oxide region therein coats each corner of the grounding ring.

18. The integrated electronic device of claim 15, further comprising a plurality of pads having a top surface coated with a coating region made of the second metallic material.

19. The integrated electronic device according to claim 15, further comprising: An inner frame that laterally surrounds the bare die pads; An outer frame that laterally surrounds the inner frame; Multiple connecting rods are inserted between the outer frame and the inner frame; as well as Another top coating, made of the second metallic material, is arranged to contact the top surfaces of the inner frame and the outer frame; The portion of the inner frame at the location where it connects to the connecting rod is not covered by the other top coating; and The oxidized area is coated with the portion of the inner frame.

20. The integrated electronic device of claim 19, wherein the other top coating does not cover the top surface of the connector, and wherein the oxide region coats the top surface of the connector.

21. The integrated electronic device of claim 19, wherein the inner frame and the outer frame have different heights, and wherein each connecting rod includes a corresponding inclined portion to transition between the different heights.

22. A method for manufacturing an integrated electronic device, comprising the following steps: A bare die is attached to a die pad of a leadframe, the die pad being made of a first metal material and including a top surface, wherein the leadframe includes a top coating, the top coating being made of a second metal material and arranged to contact the top surface, wherein the second metal material has a lower oxidation rate than the first metal material, and wherein the top coating covers the entire top surface except for a plurality of corners of the top surface of the die pad, the plurality of corners being not covered by the top coating and separated from each other; Perform a wire bonding operation to electrically connect the die to the lead frame, wherein performing the wire bonding includes performing a heat treatment that results in the formation of an oxide region that coats the corner of the top surface of the die pad and laterally contacts the top coating; as well as Encapsulation is performed using a dielectric encapsulation region that directly contacts and covers the bare die, the oxidized region, and the top coating adjacent to the oxidized region.

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