Lead frame and packaging structure using same
By designing the base island connecting ribs of T-shaped or T-shaped cross-sectional structures, the deformation and abnormal risks of base island connecting ribs caused by large QFN packaging size are solved, and the reliability of the package structure is improved.
Patent Information
- Application Number
- CN202421856062.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-01
- Publication Date
- 2025-06-06
- Estimated Expiration
- 2034-08-01
AI Technical Summary
Larger QFN package sizes lead to excessive length of base island connecting ribs and prone to deformation, which in turn leads to an increase in the risk of abnormalities associated with solder joints.
A lead frame is designed in which the base island connecting rib is composed of the main reinforcement and the reinforcement rib arranged on the lower surface of the main reinforcement. The width of the reinforcement rib is smaller than the width of the main reinforcement, so that the cross-section of the base island connecting rib is T-shaped or T-shaped, enhancing bending resistance and reducing deformation risk.
By enhancing the bending resistance and support stability of the base island connecting ribs, the probability of abnormalities related to solder joints caused by excessive length of the base island connecting ribs is reduced, and the reliability of the lead frame and packaging structure is improved.
Smart Images
Figure CN222953096U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the packaging field, in particular to a lead frame and a packaging structure using the lead frame. Background Art
[0002] QFN (Quad Flat No-lead) packaging is an advanced packaging form. It has the advantages of small size, high density, good thermal conductivity, etc. It is widely used in the field of integrated circuit packaging. At present, with the increasing demand for automotive products, the requirements for product packaging are also getting higher and higher, and the package size tends to be larger. In order to avoid the welding wire being too long for the larger QFN package size, an inner extension pin wire bonding design is required, and the synchronous base island connecting rib (TieBar) also needs to be lengthened. If the TieBar is too long, the TieBar itself is easy to deform, and thus the base island is insufficiently supported. Then the base island shakes during wire bonding, causing abnormalities related to the solder joints, such as poor ball shape, ball detachment, peeling, non-stick solder joints (Non-Stick On Pad, NSOP), cracks and other risks.
[0003] Therefore, how to reduce the probability of abnormalities related to welds caused by excessively long base island connecting bars has become one of the technical problems that urgently need to be solved. Summary of the invention
[0004] The technical problem to be solved by the utility model is to provide a lead frame and a packaging structure using the lead frame, which can increase the strength of the base island connecting ribs, avoid deformation of the base island connecting ribs, and thereby reduce the probability of abnormalities related to solder joints caused by excessive length of the base island connecting ribs, thereby improving the reliability of the lead frame and the packaging structure.
[0005] In order to solve the above problems, an embodiment of the utility model provides a lead frame, including: a base island; a base island connecting rib connected to the outer edge of the base island, the base island connecting rib including a main rib and a reinforcing rib arranged on the lower surface of the main rib, the main rib and the reinforcing rib both extend from the outer edge of the base island in a direction away from the base island, and the width of the reinforcing rib is smaller than the width of the main rib.
[0006] In one embodiment, the reinforcing rib is located in the middle area or edge area of the lower surface of the main rib.
[0007] In one embodiment, the main ribs and the reinforcing ribs are integrally formed.
[0008] In one embodiment, in the extension direction of the main rib and the reinforcing rib, the length of the reinforcing rib is less than or equal to the length of the main rib.
[0009] In one embodiment, the sum of the thickness of the main rib and the reinforcing rib is less than the maximum thickness of the lead frame.
[0010] In one embodiment, the thickness of the main rib is half of the maximum thickness of the lead frame.
[0011] In one embodiment, the thickness of the reinforcing rib is less than half of the maximum thickness of the lead frame.
[0012] In one embodiment, the thickness of the reinforcing rib is one quarter of the maximum thickness of the lead frame.
[0013] In one embodiment, a bottom surface of the reinforcing rib is higher than the lowest point of the bottom surface of the lead frame.
[0014] In one embodiment, the width of the reinforcing rib is less than or equal to half of the width of the main rib.
[0015] The embodiment of the utility model further provides a packaging structure, which adopts the above-mentioned lead frame.
[0016] In the lead frame and the packaging structure using the lead frame provided by the embodiments of the utility model, the base island connecting rib is composed of a main rib and a reinforcing rib arranged on the lower surface of the main rib, and the width of the reinforcing rib is smaller than the width of the main rib, so that the cross-section of the base island connecting rib is a T-shaped or T-shaped configuration, which enhances the bending resistance of the base island connecting rib, reduces the deformation risk of the base island connecting rib, improves the supporting stability of the base island connecting rib to the base island, can reduce the probability of abnormalities related to solder joints caused by excessive length of the base island connecting rib, and improves the reliability of the lead frame and the packaging structure. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0018] Figure 1 It is a structural schematic diagram of a lead frame provided by an embodiment of the utility model;
[0019] Figure 2 yes Figure 1 Enlarged schematic diagram of the middle C area;
[0020] Figure 3 is along Figure 2 An enlarged schematic diagram of the cross-sectional view of line A-A1;
[0021] Figure 4 is along Figure 2 An enlarged schematic diagram of the cross-sectional view of line B-B1;
[0022] Figure 5 It is a cross-sectional schematic diagram of a base island connecting rib of a lead frame provided by another embodiment of the utility model. DETAILED DESCRIPTION
[0023] The specific implementation of the lead frame provided by the utility model and the packaging structure using the lead frame are described in detail below with reference to the accompanying drawings.
[0024] Figure 1 1 is a schematic diagram of the structure of a lead frame provided by an embodiment of the utility model. Figure 2 yes Figure 1 The enlarged schematic diagram of the C area in the middle. Figure 3 is along Figure 2 An enlarged schematic diagram of the cross-sectional view of the A-A1 line in FIG. Figure 4 is along Figure 2 For an enlarged schematic diagram of the cross-section along line B-B1, please refer to Figure 1 to Figure 4 The lead frame includes: a base island 100; a base island connecting rib 110 connected to the outer edge of the base island 100, the base island connecting rib 110 includes a main rib 111 and a reinforcing rib 112 arranged on the lower surface of the main rib 111, the main rib 111 and the reinforcing rib 112 both extend from the outer edge of the base island 100 in a direction away from the base island 100, and the width W1 of the reinforcing rib 112 is smaller than the width W2 of the main rib 111.
[0025] In the lead frame provided by the embodiment of the utility model, the base island connecting rib 110 is composed of a main rib 111 and a reinforcing rib 112 arranged on the lower surface of the main rib 111, and the width W1 of the reinforcing rib 112 is smaller than the width W2 of the main rib 111, so that the cross-section of the base island connecting rib 110 is a T-shaped or T-shaped configuration, which strengthens the bending resistance of the base island connecting rib 110, reduces the deformation risk of the base island connecting rib 110, improves the supporting stability of the base island connecting rib 110 to the base island 100, can reduce the probability of abnormalities related to solder joints caused by the excessive length of the base island connecting rib 110, and improves the reliability of the lead frame.
[0026] The extension direction of the main rib 111 and the reinforcing rib 112 is as follows: Figure 3 In the D1 direction, the width W1 of the reinforcing rib 112 refers to the dimension of the reinforcing rib 112 in the transverse direction. Figure 3 As shown, the width W1 of the reinforcing rib 112 refers to the dimension of the reinforcing rib 112 in the direction D2; the width W2 of the main rib 111 refers to the dimension of the main rib 111 in the transverse direction. Figure 3As shown, the width W2 of the main rib 111 refers to the dimension of the main rib 111 in the direction D2, wherein the direction D2 is perpendicular to the direction D1.
[0027] The base island connecting rib 110 is connected to the outer edge of the base island 100, and is used to connect the base island 100 to other areas of the lead frame. In one embodiment, the base island connecting rib 110 is connected to the corner of the base island 100, that is, the base island connecting rib 110 is located at the corner of the base island 100.
[0028] The reinforcing rib 112 is disposed on the lower surface of the main rib 111, and the width W1 of the reinforcing rib 112 is smaller than the width W2 of the main rib 111, so that the cross section of the island connecting rib 110 is a T-shaped configuration or a T-shaped configuration. Figure 3 As shown, the reinforcing rib 112 is located in the middle area of the lower surface of the main rib 111, and the width W1 of the reinforcing rib 112 is smaller than the width W2 of the main rib 111. The cross section of the island connecting rib 110 is a T-shaped configuration, which can greatly increase the bending resistance of the island connecting rib 110, reduce the deformation risk of the island connecting rib 110, and improve the supporting stability of the island connecting rib 110 to the island 100. For another example, in another embodiment, Figure 5 As shown, it is a cross-sectional schematic diagram of a base island connecting rib 110 of a lead frame provided in another embodiment of the present invention, wherein the reinforcing rib 112 is located at the edge area of the lower surface of the main rib 111, and the width W1 of the reinforcing rib 112 is smaller than the width W2 of the main rib 111, and the cross-section of the base island connecting rib 110 is a T-shaped configuration to adapt to different design requirements of the lead frame.
[0029] In some embodiments, the main rib 111 and the reinforcing rib 112 are integrally formed to further reduce the risk of deformation of the base island connecting rib 110. Specifically, when manufacturing the lead frame, the main rib 111 and the reinforcing rib 112 are obtained by etching the lead frame body in one step. Since the main rib 111 and the reinforcing rib 112 are an integral structure, there is no substantial interface at the intersection of the two. In order to further clearly show the positional relationship between the main rib 111 and the reinforcing rib 112, Figure 3 and Figure 4 The dotted line is used to schematically illustrate the intersection of the main rib 111 and the reinforcing rib 112 .
[0030] In some embodiments, in the extension direction of the main rib 111 and the reinforcing rib 112, the length of the reinforcing rib 112 is less than or equal to the length of the main rib 111. Specifically, in one embodiment, Figure 4 As shown, in the extension direction of the main rib 111 and the reinforcing rib 112 (such as Figure 4 In the direction D1 of the center, the length L1 of the reinforcing rib 112 is equal to the length L2 of the main rib 111. In another embodiment, in the extending direction of the main rib 111 and the reinforcing rib 112, the length of the reinforcing rib 112 may also be less than the length of the main rib 111.
[0031] In some embodiments, the reinforcing rib 112 includes a plurality of discontinuous sub-reinforcing ribs. Specifically, in one embodiment, in the extension direction of the main rib 111, a plurality of sub-reinforcing ribs are discretely arranged on the lower surface of the main rib 111 to form the reinforcing rib 112, and the intervals between the sub-reinforcing ribs facilitate mold flow in the subsequent packaging process.
[0032] In some embodiments, the width W1 of the reinforcing rib 112 is less than or equal to half of the width W2 of the main rib 111, so as to ensure that the base island connecting rib 110 has sufficient supporting strength for the base island 100 while reducing the area occupied by the reinforcing rib 112, thereby avoiding the reinforcing rib 112 from having a significant impact on the shape of the lead frame and the appearance of the packaging structure using the lead frame.
[0033] In some embodiments, the sum of the thickness of the main rib 111 and the reinforcing rib 112 is less than the maximum thickness of the lead frame, and the thickness of the base island connecting rib 110 does not exceed the maximum thickness of the lead frame, and the arrangement of the reinforcing rib 112 will not affect the appearance of the packaging structure. Figure 3 As shown, in the direction perpendicular to the surface of the base island connecting rib 110, as shown Figure 3 In the D3 direction, the thickness of the reinforcing rib 112 is H1, the thickness of the main rib 111 is H2, and the sum of the thickness of the main rib 111 and the reinforcing rib 112 is less than the maximum thickness of the lead frame. The D3 direction is perpendicular to both the D1 direction and the D2 direction. The maximum thickness of the lead frame refers to the thickness of the thickest area in the lead frame. In some embodiments, the lead frame substrate is etched to form the base island connecting ribs and other structures of the lead frame (such as pins), and there is an unetched area in the lead frame, which is the area with the largest thickness of the lead frame, that is, the maximum thickness of the lead frame is the same as the thickness of the lead frame substrate.
[0034] In some embodiments, the thickness H2 of the main rib 111 is half of the maximum thickness of the lead frame. In the process, the lead frame substrate is etched by a half-etching process to form the base island connecting rib 110, so that the thickness of the main rib 111 is half of the maximum thickness of the lead frame. In some embodiments, the thickness H1 of the reinforcing rib 112 is less than half of the maximum thickness of the lead frame, so that the sum of the thickness of the main rib 111 and the reinforcing rib 112 is less than the maximum thickness of the lead frame, thereby avoiding the base island connecting rib 110 being too thick and affecting the appearance of the packaging structure using the lead frame. Further, in some embodiments, the thickness H1 of the reinforcing rib 112 is one-fourth of the maximum thickness of the lead frame. In some embodiments, the bottom surface of the reinforcing rib 112 is higher than the lowest point of the bottom surface of the lead frame to avoid the base island connecting rib 110 being too thick and affecting the appearance of the packaging structure using the lead frame.
[0035] In the lead frame provided by the embodiment of the utility model, the base island connecting rib 110 is composed of a main rib 111 and a reinforcing rib 112 arranged on the lower surface of the main rib 111, and the width W1 of the reinforcing rib 112 is smaller than the width W2 of the main rib 111, so that the cross-section of the base island connecting rib 110 is a T-shaped or T-shaped configuration, which strengthens the bending resistance of the base island connecting rib 110, reduces the deformation risk of the base island connecting rib 110, improves the supporting stability of the base island connecting rib 110 to the base island 100, can reduce the probability of abnormalities related to solder joints caused by the excessive length of the base island connecting rib 110, and improves the reliability of the lead frame.
[0036] The embodiment of the utility model further provides a packaging structure, wherein the packaging structure adopts the lead frame. The packaging structure may be a QFN package. Furthermore, the QFN package is a large-size package, and its base island connecting rib 110 is relatively long. The utility model can reduce the probability of abnormalities related to solder joints caused by the excessive length of the base island connecting rib 110 by setting the main rib 111 and the reinforcing rib 112, thereby improving the reliability of the packaging structure.
[0037] It should be noted that the terms "including" and "having" and their variations involved in the documents of the present utility model are intended to cover non-exclusive inclusions. The terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, unless the context clearly indicates, and it should be understood that the data used in this way can be interchanged under appropriate circumstances. The term "one or more" depends at least in part on the context, and can be used to describe features, structures or characteristics in a singular sense, or can be used to describe a combination of features, structures or features in a plural sense. The term "based on" can be understood as not necessarily intended to express a set of exclusive factors, but can alternatively, also at least in part depending on the context, allow the presence of other factors that are not necessarily explicitly described. In addition, in the absence of conflict, the embodiments of the present utility model and the features in the embodiments can be combined with each other. In addition, in the above description, the description of known components and technologies is omitted to avoid unnecessary confusion of the concept of the present utility model. In the above embodiments, each embodiment focuses on the differences from other embodiments, and the same / similar parts between the embodiments can be referred to each other.
[0038] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.
Claims
1. A lead frame, characterized in that: include: Key Island; The base island connecting ribs are connected to the outer edge of the base island, and the base island connecting ribs include main ribs and reinforcing ribs arranged on the lower surface of the main ribs. The main ribs and the reinforcing ribs extend from the outer edge of the base island in a direction away from the base island, and the width of the reinforcing ribs is smaller than the width of the main ribs.
2. The lead frame according to claim 1, characterized in that: The reinforcing ribs are located in the middle area or edge area of the lower surface of the main ribs.
3. The lead frame according to claim 1, wherein: The main ribs and the reinforcing ribs are integrally formed.
4. The lead frame according to claim 1, wherein: In the extension direction of the main rib and the reinforcing rib, the length of the reinforcing rib is less than or equal to the length of the main rib.
5. The lead frame according to claim 1, wherein: The sum of the thickness of the main rib and the reinforcing rib is less than the maximum thickness of the lead frame.
6. The lead frame according to claim 1, wherein: The thickness of the main rib is half of the maximum thickness of the lead frame.
7. The lead frame according to claim 1, wherein: The thickness of the reinforcing rib is less than half of the maximum thickness of the lead frame.
8. The lead frame according to claim 1, wherein: The thickness of the reinforcing rib is one quarter of the maximum thickness of the lead frame.
9. The lead frame according to claim 1, wherein: The bottom surface of the reinforcing rib is higher than the lowest point of the bottom surface of the lead frame.
10. The lead frame according to claim 1, wherein: The width of the reinforcing rib is less than or equal to half of the width of the main rib.
11. A packaging structure, characterized in that: A lead frame according to any one of claims 1 to 10 is used.