CN220873575U - Lead frame and packaging structure - Google Patents

Abstract

The embodiment of the application discloses a lead frame, which comprises: a first die pad comprising a first surface; a second die pad spaced from the first die pad in a first direction, and including a second surface co-directional with the first surface; a support member on the same side as the first surface and the second surface and connecting the first surface and the second surface; the first I/O pad is arranged on the first surface and is spaced from the support member in a first direction and a second direction different from the first direction. According to the technical scheme, at least the supporting piece is adopted, so that the risk of deformation of the die pad can be reduced. There is also provided, in accordance with other embodiments of the present application, a package structure.

Description

Lead frame and packaging structure

Technical Field

The present application relates to the field of semiconductor technology, and more particularly, to a lead frame and a package structure.

Background

QFN packages (Quad Flat No-LEADS PACKAGE, quad Flat No-lead/pin packages) are one type of package that uses a leadframe (LEAD FRAME) that approximates the package size. The QFN package directly exposes the lower surface of the Lead (Lead) below the package, without extending the Lead.

Fig. 1 is a schematic perspective view of a portion of a lead frame 10 according to the prior art. Fig. 1 shows a conventional lead frame 10 having a plurality of die pads 11, the die pads 11 are portions of the lead frame 10 for carrying semiconductor dies, in a QFN package (not shown) having a plurality of die pads 11 prepared by using the lead frame 10 in the prior art, since the bottom sides 21 of the die pads 11 cannot be exposed to the outside after packaging, it is necessary to half-etch the bottom sides 21 of the die pads 11 and cover them with a mold layer (not shown), so that each die pad 11 can be supported by only a single external lead, the external leads are not fully shown, and only the I/O pads 12 which can be exposed compared to the mold layer for external electrical connection are shown for connection with the external leads. The more the etched portion is, the higher the probability of deformation of the die pad 11 is, the lower the yield of the lead frame 10 is, and the yield of the lead frame 10 in the prior art is less than 60%. The die pad 11 is easily deformed by sinking under stress during the manufacturing process of the lead frame 10 and the subsequent packaging process, for example, during die bonding, wire bonding, and the like. The bottom side 21 of the die pad 11 is currently supported by a supporting assembly (MESA kit), but due to possible tolerances between the half-etching depth of the die pad 11 and the MESA kit, deformation of the die pad 11 may still result, affecting the operation stability. The yield of QFN package after packaging the lead frame 10 can only be higher than 70%.

Disclosure of utility model

In view of the above problems in the prior art, embodiments of the present application provide a leadframe that at least reduces the risk of die pad deformation.

According to an aspect of the present application, there is provided a lead frame including: a first die pad comprising a first surface; a second die pad spaced from the first die pad in a first direction, and including a second surface co-directional with the first surface; a support member on the same side as the first surface and the second surface and connecting the first surface and the second surface; the first I/O pad is arranged on the first surface and is spaced from the support member in a first direction and a second direction different from the first direction. In one or more embodiments, the leadframe further includes a third die pad spaced from and aligned with the first die pad in the second direction, wherein the third die pad includes a third surface co-directional with the first surface, and the support is further coupled to the third surface. In one or more embodiments, the leadframe further includes a fourth die pad spaced apart from the second die pad in the second direction, and the fourth die pad is adjacent to the second die pad and the third die pad, wherein the fourth die pad includes a fourth surface co-directional with the first surface, and the support is further coupled to the fourth surface. In one or more embodiments, the leadframe further includes a second I/O pad disposed on the second surface, a third I/O pad disposed on the third surface, and a fourth I/O pad disposed on the fourth surface, each spaced apart from the support in the first direction and the second direction. In one or more embodiments, the first I/O pad, the second I/O pad, the third I/O pad, and the fourth I/O pad are disposed at four top corners of an assembly of the first die pad, the second die pad, the third die pad, and the fourth die pad, respectively.

In view of the above problems in the prior art, embodiments of the present application also provide a package structure having at least a recess providing a supporting position to stably support the package structure to reduce the risk of die pad deformation.

According to another aspect of the present application, there is provided a package structure including: a first die pad comprising a first surface; a second die pad spaced from the first die pad in a first direction, and including a second surface co-directional with the first surface; the first concave part and the second concave part are respectively arranged at two adjacent corner parts of the first die pad and the second die pad in a one-to-one correspondence manner, and are respectively arranged on the first surface and the second surface; the first I/O pad is arranged on the first surface and is spaced from the first concave part in a first direction and a second direction different from the first direction. In one or more embodiments, the roughness of the first die pad at the first recess is greater than the roughness of the first surface at a location outside of the first recess. In one or more embodiments, the package structure further includes a semiconductor die on the first die pad and the second die pad, respectively, the semiconductor die and the first I/O pad being on opposite sides of the first die pad. In one or more embodiments, the package structure further includes a third die pad spaced from and aligned with the first die pad in the second direction, wherein the third die pad includes a third surface co-directional with the first surface, and a third recess is provided on the third surface at a corner of the third die pad adjacent to the first die pad and the second die pad. In one or more embodiments, the package structure further includes a mold layer encasing the first die pad and the second die pad, the mold layer including a fifth recess below the first recess and the second recess, the fifth recess in communication with the first recess and the second recess forming a groove.

The utility model can at least solve the technical problem that the die pad in the lead frame with a plurality of die pads is easy to deform due to external force. The technical effects of the utility model include: the lead frame provided by the utility model at least adopts the supporting piece, so that the risk of deformation of the die pad can be reduced. In addition, the utility model has the technical effects that: the packaging structure provided by the utility model is provided with at least a concave part for providing a supporting position so as to stably support the packaging structure, thereby reducing the risk of deformation of the die pad.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. It is noted that the various components are not drawn to scale and are for illustrative purposes only, according to industry standard practices. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. The different colors in the perspective view are only for better rendering the stereoscopic effect.

Fig. 1 is a schematic perspective view of a portion of a lead frame according to the prior art.

Fig. 2A is a schematic perspective view of a portion of a leadframe according to an embodiment of the application.

Fig. 2B is a bottom view of the lead frame shown in fig. 2A.

Fig. 3A, 4A, 5A and 6A are schematic perspective views at various steps of forming a package structure according to one embodiment of the present application.

Fig. 3B, 4B, 5B and 6B are schematic bottom views at various steps of forming a package structure corresponding to fig. 3A, 4A, 5A and 6A, respectively.

Fig. 7 is a schematic cross-sectional view of a package structure according to an embodiment of the present application, taken along line A-A' in fig. 6A.

Fig. 8 is a schematic cross-sectional view of a package structure according to one embodiment of the present application, taken along line B-B' in fig. 6A.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which are derived by a person skilled in the art based on the embodiments of the application, fall within the scope of protection of the application.

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of elements and arrangements will be described below to simplify the present disclosure. These are, of course, merely examples and are not intended to limit the utility model. For example, in the following description, forming a first component over or on a second component may include embodiments in which the first component and the second component are in direct contact, and may also include embodiments in which additional components are formed between the first component and the second component such that the first component and the second component may not be in direct contact. Moreover, the present utility model may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

In addition, the embodiments of the present application and the features in the embodiments may be combined with each other without collision. The application will be described in detail below with reference to the drawings in connection with embodiments. It should be understood that the particular arrangements shown in the drawings are meant to be illustrative only and not limiting. In describing the specific drawings, other structures shown in the drawings, which are not described, may be provided according to actual needs and are not intended to limit the present application.

Fig. 2A is a schematic perspective view of a portion of a leadframe 100 according to an embodiment of the application. Fig. 2B is a bottom view of the leadframe 100 shown in fig. 2A.

Referring to fig. 2A and 2B, the lead frame 100 of the present application includes a first die pad 111, a second die pad 112, a support member 120, and a first I/O pad 131, wherein the first die pad 111 includes a first surface 1111, the second die pad 112 is spaced apart from the first die pad 111 in a first direction D1, and the second die pad 112 includes a second surface 1121 in the same direction as the first surface 1111, the support member 120 is on the same side as the first surface 1111 and the second surface 1121, and connects the first surface 1111 and the second surface 1121, and the first I/O pad 131 is disposed on the first surface 1111 and spaced apart from the support member 120 in the first direction D1 and a second direction D2 different from the first direction D1. The lead frame 100 of the present application at least adopts the supporting member 120, which can reduce the risk of deformation of the first die pad 111 and the second die pad 112, and the supporting member 120 is connected to the first surface 1111 of the first die pad 111 and the second surface 1121 of the second die pad 112, so as to support the first die pad 111 and the second die pad 112, and help the first die pad 111 and the second die pad 112 resist stress and avoid deformation due to sinking in the operations such as die bonding and wire bonding.

In one or more embodiments, the second direction D2 is perpendicular to the first direction D1. In other embodiments, the second direction D2 may not be perpendicular to the first direction D1.

In one or more embodiments, the lead frame 100 may further include a third die pad 113, the third die pad 113 being spaced apart from the first die pad 111 and aligned with the first die pad 111 in the second direction D2, wherein the third die pad 113 includes a third surface 1131 co-directional with the first surface 1111, and the support 120 is further connected to the third surface 1131.

In one or more embodiments, the leadframe 100 may further include a fourth die pad 114 spaced apart from the second die pad 112 in the second direction D2, and the fourth die pad 114 is adjacent to the second die pad 112 and the third die pad 113, wherein the fourth die pad 114 includes a fourth surface 1141 co-directional with the first surface 1111, and the support 120 is further connected to the fourth surface 1141.

The lead frame 100 in the embodiment of the application is provided with at least the supporting member 120 connected to the first surface 1111 of the first die pad 111, the second surface 1121 of the second die pad 112, the third surface 1131 of the third die pad 113 and the fourth surface 1141 of the fourth die pad 114, so as to support the first die pad 111, the second die pad 112, the third die pad 113 and the fourth die pad 114, and help the first die pad 111, the second die pad 112, the third die pad 113 and the fourth die pad 114 resist the stress, and reduce the risk of deformation caused by sinking of the stress.

In one or more embodiments, a central axis (not shown) of the assembly 110 of the first, second, third, and fourth die pads 111, 112, 113, 114 coincides with a central axis (not shown) of the support 120. In some embodiments, the support 120 is a cylinder, as shown in fig. 2A. It should be appreciated that the number of supports 120 is not limited to one, and the shape of the supports 120 is not limited to a cylinder, and the supports 120 may be any suitable shape, such as prismatic, tetragonal, etc.

In one or more embodiments, the first surface 1111, the second surface 1121, the third surface 1131, and the fourth surface 1141 are flush with one another.

In one or more embodiments, leadframe 100 may further include a second I/O pad 132 disposed on second surface 1121, a third I/O pad 133 disposed on third surface 1131, and a fourth I/O pad 134 disposed on fourth surface 1141, each spaced apart from support 120 in first direction D1 and in second direction D2.

In one or more embodiments, the first, second, third, and fourth I/O pads 131, 132, 133, and 134 are disposed at four top corners of the assembly 110 of the first, second, third, and fourth die pads 111, 112, 113, and 114, respectively. In the example shown in fig. 2A, the first die pad 111, the second die pad 112, the third die pad 113, and the fourth die pad 114 are quadrangles of the same size in a plan view, and in practice, the shape of the die pads is not limited to quadrangles, and may be polygonal or any other suitable shape.

In one or more embodiments, bottom surface 1201 of support 120, remote from first surface 1111, is flush with bottom surface 1311 of first I/O pad 131, bottom surface 1321 of second I/O pad 132, bottom surface 1331 of third I/O pad 133, and bottom surface 1341 of fourth I/O pad 134. The support 120 of the present application forms a stable five-point support for the assembly 110 with the first, second, third and fourth I/O pads 131, 132, 133 and 134, reducing the risk of deformation of the individual die pads.

In one or more embodiments, leadframe 100 is a unitary piece. In some embodiments, the material of the leadframe 100 includes Fe, ni, cu, or alloys thereof. In one or more embodiments, leadframe 100 is a unitary piece of copper. In some embodiments, a monolithic metal plate is provided, the support 120 is formed by upper half-etching to form a lower solid, and the plurality of die pads (the first die pad 111, the second die pad 112, the third die pad 113 and the fourth die pad 114) are formed by matching with the lower half-etching, except for the support 120, each of the plurality of die pads is supported by only one external pin (not shown), and the support 120 is connected with the plurality of die pads in series to provide additional solid support, so that the strength of the lead frame 100 is enhanced, and the deformation risk of each die pad is reduced. The manufacturing yield of the lead frame 100 of the present application can be more than 90%, and can be increased by at least 30% compared to the yield of less than 60% in the prior art. And then the packaging is completed by matching with the subsequent processes of molding, etching, coating forming and the like. After packaging, the supporting member 120 is removed to form an independent die pad, so that the process yield can be improved, and the yield of the prepared packaging structure of the application can be more than 90%. Die bonding and wire bonding operations can be increased by 25% when preparing the package structure. When the packaging structure is prepared, the probability of glue overflow (mold flash) in the mold packaging process can be reduced by 30%.

Fig. 3A, 4A, 5A, and 6A are perspective views at various steps of forming a package structure 200 according to one embodiment of the application. Fig. 3B, 4B, 5B, and 6B are bottom schematic views at various steps of forming the package structure 200 corresponding to fig. 3A, 4A, 5A, and 6A, respectively.

Referring to fig. 3A, using the lead frame 100 (with support 120) shown in fig. 2A, the structure shown in fig. 3A is formed after die bonding, wire bonding, and die sealing processes, 4 semiconductor dies 150 are respectively located on the first, second, third, and fourth die pads 111, 112, 113, 114, each wire 230 electrically connects the first, second, third, and fourth die pads 111, 112, 113, 114 to the first, second, third, and fourth I/O pads 131, 132, 133, and 134, respectively, and the first, second, third, and fourth die pads 111, 112, 113, 114, and the die seal 240 encapsulates the semiconductor dies 150 and wires 230. In some embodiments, semiconductor die 150 may be a power die or the like. In some embodiments, the mold layer 240 may be an epoxy molding compound (Epoxy Molding Compound, EMC). It will be appreciated that the number of die pads and the connection relationship of the leads to the die pads are for simplicity and ease of description only and are not intended to be limiting, as any suitable modification may be made according to design requirements without departing from the spirit of the application. During the die bonding, routing, and molding processes, the first, second, third, fourth, and fourth I/O pads 131, 132, 133, 134, and 120 stably support the first, second, third, and fourth die pads 111, 112, 113, and 114 due to the presence of the support 120, reducing the risk of deformation of the first, second, third, and fourth die pads 111, 112, 113, and 114. In some embodiments, the mold layer 240 is further formed on the lower sides of the first, second, third, and fourth die pads 111, 112, 113, and 114, and the first, second, third, and fourth die pads 111, 112, 113, and 114 of the lead frame 100 are also covered by the mold layer 240. Referring to fig. 3B, only the bottom surface 1311 of the first I/O pad 131, the bottom surface 1321 of the second I/O pad 132, the bottom surface 1331 of the third I/O pad 133, the bottom surface 1341 of the fourth I/O pad 134, and the bottom surface 1201 of the support 120 are exposed compared to the mold seal 240. In some embodiments, the first I/O pad 131, the second I/O pad 132, the third I/O pad 133, and the fourth I/O pad 134 are for external electrical connection.

Referring to fig. 4A, tin plating is performed by an electroplating process such that the bottom surface 1311 of the first I/O pad 131, the bottom surface 1321 of the second I/O pad 132, the bottom surface 1331 of the third I/O pad 133, the bottom surface 1341 of the fourth I/O pad 134, and the bottom surface 1201 of the support member 120 are covered with the tin layer 310, the tin layer 310 being resistant to copper oxidation, etching, etc., and the tin layer 310 avoiding the first I/O pad 131, the second I/O pad 132, the third I/O pad 133, and the fourth I/O pad 134 from being damaged in a subsequent etching step (see fig. 5A). The plate-shaped tin layer 310 in fig. 4A is only illustrative, and in practice, the tin layer 310 exists only on the first I/O pad 131, the second I/O pad 132, the third I/O pad 133, the fourth I/O pad 134, and the support 120, covering the bottom surface 1311 of the first I/O pad 131, the bottom surface 1321 of the second I/O pad 132, the bottom surface 1331 of the third I/O pad 133, the bottom surface 1341 of the fourth I/O pad 134, and the bottom surface 1201 of the support 120, which are exposed compared to the mold layer 240, and the first die pad 111, the second die pad 112, the third die pad 113, and the fourth die pad 114 are covered with the mold layer 240. Referring to fig. 4B, in a bottom view schematic diagram, the tin layer 310 and the mold layer 240 can be seen, wherein the tin layer 310 is located only at the first I/O pad 131, the second I/O pad 132, the third I/O pad 133, the fourth I/O pad 134, and the support 120 shown in fig. 3B.

Referring to fig. 5A, the tin layer 310 (see fig. 4B) located on the bottom surface 1201 of the support 120 is removed (e.g., by a laser process), and the remaining tin layer 310 serves as an etch mask for removing the support 120. Similar to fig. 4A, the plate-like remaining tin layer 310 in fig. 5A is only schematic, and in practice, after removing the tin layer 310 (see fig. 4B) located on the bottom surface 1201 of the support 120, the remaining tin layer 310 is present only on the first I/O pad 131, the second I/O pad 132, the third I/O pad 133, and the fourth I/O pad 134. Referring to fig. 5B, in a bottom view schematic diagram, the tin layer 310 and the mold layer 240 can be seen, wherein the tin layer 310 is only located at the positions of the first I/O pad 131, the second I/O pad 132, the third I/O pad 133 and the fourth I/O pad 134 shown in fig. 3B, and the supporting member 120 is exposed.

Referring to fig. 6A, the supporting member 120 (see fig. 5A) is removed by an etching process, a groove 140 is formed in the lower surface of the mold seal layer 240, the remaining tin layer 310 (see fig. 5A) is removed, and a coating 330 (not shown in fig. 6A, see fig. 6B) is formed in the groove 140, completing the fabrication of the package structure 200. The coating 330 (see fig. 6B) serves to prevent the first, second, third and fourth die pads 111, 112, 113 and 114 from being exposed to avoid the occurrence of a short circuit, and, referring to fig. 6B, the first, second, third and fourth I/O pads 131, 132, 133 and 134 exposed after the remaining tin layer 310 (see fig. 5B) is removed are shown, and fig. 6B also shows the opening 1401 of the recess 140 (see fig. 6A) and the coating 330. In some embodiments, the coating 330 is a solder mask (solder resist coating, SRC)/solder mask (holder mask).

In some embodiments, the process illustrated in fig. 5A and 6A (laser process and etching process) may be replaced with a cutting process, directly using milling to remove the support 120 illustrated in fig. 5A and the tin layer 310 on the bottom surface 1201 of the support 120 (see fig. 4B).

Fig. 7 is a schematic cross-sectional view of the package structure 200 taken along line A-A' in fig. 6A, according to one embodiment of the application. The line A-A' in fig. 6A passes through the first and second die pads 111 and 112, and where the support 120 (see fig. 5A) is located, and does not pass through the semiconductor die 150. Fig. 8 is a schematic cross-sectional view of the package structure 200 taken along line B-B' in fig. 6A, according to one embodiment of the application. Line B-B' in fig. 6A passes through the third and fourth die pads 113 and 114, and where the support 120 (see fig. 5A) is located, and does not pass through the semiconductor die 150.

In the step of removing the support 120 (see fig. 5A) through the etching process of fig. 6A, after removing the support 120 (see fig. 5A), referring to fig. 7 and 8, first, second, third and fourth recesses 141, 142, 143 and 144 are also formed on the first, second, third and fourth die pads 111, 112, 113 and 114, respectively.

The following explains with reference to a perspective view of the package structure 200 shown in fig. 6A and a cross-sectional view of the package structure 200 shown in fig. 7 and 8. The package structure 200 of the present application may include a first die pad 111, a second die pad 112, a first I/O pad 131, and a first recess 141 and a second recess 142, wherein the first die pad 111 includes a first surface 1111, the second die pad 112 is spaced apart from the first die pad 111 in a first direction D1, and the second die pad 112 includes a second surface 1121 in the same direction as the first surface 1111; the first concave portion 141 and the second concave portion 142 are provided at two adjacent corners of the first die pad 111 and the second die pad 112, respectively, in one-to-one correspondence, and the first concave portion 141 and the second concave portion 142 are on the first surface 1111 and the second surface 1121, respectively; the first I/O pad 131 is disposed on the first surface 1111 and spaced apart from the first recess 141 in the first direction D1 and the second direction D2 different from the first direction D1. The package structure 200 of the present application has at least the first recess 141 and the second recess 142 to provide a supporting position to stably support the package structure 200, so as to reduce the risk of deformation of the first die pad 111 and the second die pad 112.

In one or more embodiments, the roughness of the first die pad 111 at the first recess 141 is greater than the roughness of the first surface 1111 at the outside of the first recess 141.

In one or more embodiments, the bottom surface 1412 of the first recess 141 is flush with the bottom surface 1422 of the second recess 142.

In one or more embodiments, the package structure 200 may further include a semiconductor die 150 on the first and second die pads 111, 112, respectively, the semiconductor die 150 being located on opposite sides of the first die pad 111 from the first I/O pad 131.

In one or more embodiments, the package structure 200 may further include a third die pad 113 spaced apart from the first die pad 111 and aligned with the first die pad 111 in the second direction D2, wherein the third die pad 113 includes a third surface 1131 co-directional with the first surface 1111, and a third recess 143 on the third surface 1131 is provided at a corner of the third die pad 113 adjacent to the first die pad 111 and the second die pad 112.

In one or more embodiments, the package structure 200 may further include a fourth die pad 114 spaced apart from the second die pad 112 in the second direction D2, and the fourth die pad 114 is adjacent to the second die pad 112 and the third die pad 113, wherein the fourth die pad 114 includes a fourth surface 1141 co-directional with the first surface 1111, and a fourth recess 144 is provided on the fourth surface 1141 at a corner of the fourth die pad 114 adjacent to the first die pad 111, the second die pad 112, and the third die pad 113.

In one or more embodiments, the package structure 200 may further include a mold layer 240 encasing the first die pad 111 and the second die pad 112, the mold layer 240 including a fifth recess 145 below the first recess 141 and the second recess 142, the fifth recess 145 in communication with the first recess 141 and the second recess 142 forming the groove 140. In one or more embodiments, the sidewall 1451 of the fifth recess 145 is aligned up and down with the sidewall 1411 of the first recess 141 and the sidewall 1421 of the second recess 142. In one or more embodiments, the roughness of the mold seal 240 at the fifth recess 145 is greater than the roughness of the mold seal 240 at the outside of the fifth recess 145.

In one or more embodiments, the first recess 141 has a coating 330 therein that covers the sidewalls 1411 and bottom surface 1412 of the first recess 141, and the coating 330 may be a solder mask. The coating 330 serves to prevent the first die pad 111 from being exposed to avoid short circuit.

The lead frame provided by the utility model at least adopts the supporting piece, so that the risk of deformation of the die pad can be reduced. The packaging structure provided by the utility model is provided with at least a concave part for providing a supporting position so as to stably support the packaging structure, thereby reducing the risk of deformation of the die pad.

In addition, the technical scheme of the utility model is suitable for QFN packaging structures of two processes of punching (punch) and cutting (saw).

The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the application.

Claims (10)

1. A lead frame, comprising:

A first die pad comprising a first surface;

A second die pad spaced apart from the first die pad in a first direction, and including a second surface co-directional with the first surface;

a support member on the same side as the first surface and the second surface and connecting the first surface and the second surface;

The first I/O pad is arranged on the first surface and is spaced from the support member in a first direction and a second direction different from the first direction.

2. The leadframe of claim 1, further comprising a third die pad spaced from and aligned with the first die pad in the second direction,

Wherein the third die pad includes a third surface co-directional with the first surface, the support also being connected to the third surface.

3. The leadframe of claim 2, further comprising a fourth die pad spaced from the second die pad in the second direction, and the fourth die pad being adjacent to the second die pad and the third die pad,

Wherein the fourth die pad includes a fourth surface co-directional with the first surface, the support also being connected to the fourth surface.

4. The leadframe of claim 3, further comprising a second I/O pad disposed on the second surface, a third I/O pad disposed on the third surface, and a fourth I/O pad disposed on the fourth surface, each spaced from the support in the first direction and the second direction.

5. The leadframe of claim 4, wherein the first I/O pad, the second I/O pad, the third I/O pad, and the fourth I/O pad are disposed at four top corners of an assembly of the first die pad, the second die pad, the third die pad, and the fourth die pad, respectively.

6. A package structure, comprising:

A first die pad comprising a first surface;

A second die pad spaced apart from the first die pad in a first direction, and including a second surface co-directional with the first surface;

A first recess and a second recess, which are respectively arranged at two adjacent corners of the first die pad and the second die pad in a one-to-one correspondence manner, and are respectively arranged on the first surface and the second surface;

And a first I/O pad disposed on the first surface and spaced apart from the first recess in a first direction and a second direction different from the first direction.

7. The package structure of claim 6, wherein a roughness of the first die pad at the first recess is greater than a roughness of the first surface at a location outside of the first recess.

8. The package structure of claim 6, further comprising semiconductor die on the first die pad and the second die pad, respectively, the semiconductor die and the first I/O pad being on opposite sides of the first die pad.

9. The package structure of claim 6, further comprising a third die pad spaced from and aligned with the first die pad in the second direction,

Wherein the third die pad includes a third surface co-directional with the first surface, and a third recess on the third surface is provided at a corner of the third die pad adjacent to the first die pad and the second die pad.

10. The package structure of claim 6, further comprising a mold layer encasing the first die pad and the second die pad, the mold layer comprising a fifth recess below the first recess and the second recess, the fifth recess in communication with the first recess and the second recess forming a groove.