Lead frame structure capable of increasing combinability

Abstract

The utility model discloses a lead frame structure capable of increasing combinability, and relates to the field of semiconductor packaging, a plurality of groups of mutually connected lead frame units are arranged in a frame border, each lead frame unit comprises a plurality of basic units which have the same structure and are arranged in an array mode, and the lead frame units in adjacent columns are connected through longitudinal connecting ribs. The basic units in the adjacent rows are connected through transverse connecting ribs; and extrusion steps are arranged on the basic units. A plurality of groups of lead frame structures are cascaded, an extrusion step is designed on a basic unit in each lead frame structure, and due to the existence of the extrusion depth of the step, the binding force between the whole lead frame structure and a plastic package material can be remarkably improved. Besides, elliptical through holes are formed in the cascaded longitudinal connecting ribs, and dovetail grooves and other structures are arranged on the base islands, so that the binding force of the plastic package material can be further improved, and the problem of layering between the frame and the plastic package material is solved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor packaging, and in particular to a lead frame structure with increased bonding properties. Background Art

[0002] Lead frame is the carrier of the chip in semiconductor packaging. It uses metal materials (such as gold-copper wire, aluminum wire, aluminum tape, copper tape) to achieve electrical connection between the chip and external pins. It is a key structural component and basic material in semiconductor packaging. The design structure of the lead frame determines the technical level of the packaging and the reliability of the product. The traditional design structure easily causes delamination between the lead frame and the plastic packaging material, affecting the quality and reliability of the product. Utility Model Content

[0003] The embodiment of the present application provides a lead frame structure with increased bonding, which solves the problem of delamination between the lead frame and the plastic packaging material. A lead frame structure with increased bonding includes a frame, wherein a plurality of groups of interconnected lead frame units are arranged in the frame, wherein the lead frame units include a plurality of basic units with the same structure and arranged in an array, wherein the lead frame units in adjacent columns are connected by longitudinal connecting ribs, and the basic units in adjacent rows are connected by transverse connecting ribs; and an extrusion step is arranged on the basic unit.

[0004] Specifically, a plurality of groups of circular and / or elliptical first through holes are evenly formed on the frame, and the first through holes correspond to the lead frame units one by one; and elliptical second through holes are evenly formed on the longitudinal connecting ribs.

[0005] Specifically, the basic unit further includes a dovetail groove and a base island; the dovetail groove is located above the base island, V-shaped grooves are arranged on both sides of the base island, and the extrusion steps are symmetrically arranged on both sides of the dovetail groove.

[0006] Specifically, the depth of the dovetail groove is 0.25 to 0.40 times the thickness, and the width is 0.30 to 0.40 mm.

[0007] Specifically, a heat sink is disposed on the back of the base island, and the extrusion steps are symmetrically disposed on both sides of the heat sink, and the depth of the extrusion steps is 0.10 to 0.30 times of the thickness.

[0008] Specifically, the basic unit further includes a bonding platform and a stamp, and the bonding platform and the stamp are connected via pins.

[0009] Specifically, a locking hole is provided on the bonding platform, the locking hole is circular or semicircular, and the stamping is set to be square or rectangular.

[0010] Specifically, two or three bonding platforms are arranged side by side.

[0011] Specifically, a silver plating layer or a nickel plating layer is provided on the surface of the bonding platform.

[0012] Specifically, a plastic packaging material is arranged outside the basic unit.

[0013] The beneficial effects of the technical solution provided by the embodiment of the present application include at least: using multiple groups of lead frame structures to be cascaded, and designing an extrusion step on the basic unit in each lead frame structure, and the extrusion depth of the step can significantly improve the bonding strength between the overall lead frame structure and the plastic encapsulation material. In addition, opening an elliptical through hole on the cascaded longitudinal connecting ribs, and setting a dovetail groove and other structures above the base island can further improve the bonding strength of the plastic encapsulation material, thereby solving the problem of stratification between the frame and the plastic encapsulation material. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic structural diagram of a lead frame structure for increasing bonding properties provided in an embodiment of the present application;

[0015] Figure 2 yes Figure 1 The enlarged view of point A in the middle;

[0016] Figure 3 It is a structural diagram of the basic unit;

[0017] Figure 4 It is a cross-sectional view of the dovetail groove and the bidirectional extrusion step;

[0018] Figure 5 It is a cross-sectional view of the dovetail groove after setting the plastic sealing compound;

[0019] Figure 6 A schematic diagram of the structure of a bonding platform with different design parameters is shown.

[0020] Figure numerals: frame-1, first through hole-101, basic unit-2, transverse connecting rib-3, longitudinal connecting rib-4, second through hole-41, dovetail groove-5, extrusion step-6, base island-7, bonding platform-8, pin-9, stamping-10, locking hole-11, plastic packaging material-12. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0022] The term "multiple" as used herein refers to two or more than two. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

[0023] Figure 1 1 is a schematic diagram of a lead frame structure for increasing bonding provided in an embodiment of the present application. The lead frame structure for increasing bonding includes a frame 1, in which a plurality of groups of interconnected lead frame units are arranged. Figure 1 In the dotted box mark A, in a possible implementation, the lead frame units are arranged in a cascade form. All lead frame units have the same structure, and contain a number of basic units 2 with the same structure and arranged in an array. The lead frame units in adjacent columns are connected by longitudinal connecting ribs 4, and the basic units 2 in adjacent rows are connected by transverse connecting ribs 3.

[0024] Figure 2 yes Figure 1 The enlarged view at A in the figure shows a schematic diagram of the structure of a lead frame unit (i.e., a group). For example, the lead frame unit is arranged in an array of five rows and two columns, and twelve consecutive groups are combined into a complete lead frame structure. Of course, the size of the lead frame structure needs to be analyzed specifically according to the actual product, and the specific number and size of the array are determined according to the actual situation. In some embodiments, in order to better solve the stratification phenomenon between the lead frame and the plastic encapsulation material, an extrusion step 6 can be set on the basic unit 2, and the extrusion step 6 can improve the bonding between the frame and the plastic encapsulation material 12.

[0025] Figure 3 It is a structural schematic diagram of a basic unit, and the basic unit 2 includes a dovetail groove 5, an extrusion step 6 and a base island 7; the dovetail groove 5 is located above the base island 7, and a V-shaped groove is arranged on both sides of the base island 7, and the extrusion step 6 is symmetrically arranged on both sides of the dovetail groove 5. The number of base islands 7 in each basic unit 2 is one, and the width of the base island 7 is 5.0-6.0 mm, and the length is 3.5-4.5 mm. In addition, in some embodiments, a bonding platform and an imprint 10 can also be provided in the basic unit, and the bonding platform 8 and the imprint 10 are connected by pins 9. The pins 9 are provided with a bending structure, and the bending height is 0.20-0.50 mm, and the imprint 10 is set to a square or a rectangle.

[0026] In order to improve the bonding property of the plastic encapsulation material 12, the extrusion step 6 is designed as a double-sided structure. The back of the base island 7 is a heat sink, and the extrusion step 6 is symmetrically arranged on the structure of the heat sink to form a double-sided structure. The extrusion step 6 on the heat sink is the same as the structure on the front base island 7.

[0027] Figure 4 It is a cross-sectional view of the dovetail groove and the bidirectional extrusion step. Figure 5 It is a cross-sectional view of the dovetail groove after the plastic encapsulation material is set. The depth of the dovetail groove 5 is designed to be 0.14-0.20 mm, the width is designed to be 0.30-0.40 mm, and the depth is 0.25-0.40 times the thickness. The extrusion depth of the bidirectional extrusion step 6 is designed to be 0.05-0.15 mm, and the depth is set to be 0.10-0.30 times the thickness. In some embodiments, the bidirectional extrusion step 6 is set on both sides of the dovetail groove 5 at the front position of the base island 7, and the two ends of the dovetail groove 5 are not completely connected to the top and bottom of the bidirectional extrusion step 6, which plays a role in releasing stress. The extrusion steps 6 in the back heat sink area can be symmetrically arranged, or designed separately around the three edges of the base island 6 to enhance the bonding with the plastic encapsulation material 12. Figure 5 The design of the middle dovetail groove can significantly increase the bonding strength between the lead frame and the molding compound.

[0028] In some embodiments, a plurality of groups of circular and / or elliptical first through holes 101 may be evenly formed on the frame 1, and the first through holes 101 correspond to the lead frame units one by one; and second through holes 41 may be evenly formed on the longitudinal connecting ribs 4. The evenly distributed through holes may also increase the bonding strength with the plastic encapsulation material 12.

[0029] Based on the above design ideas, a material locking hole 11 can be provided on the bonding platform 8. The material locking hole 11 is circular or semicircular. The number of bonding platforms 8 can be designed to be 2 or 3 arranged side by side according to actual needs.

[0030] Figure 6 A schematic diagram of the structure of the bonding platform with different design parameters is shown. Figure 6 From left to right, the first one adopts the design of two bonding platforms 8. A locking hole 11 is opened on one of the bonding platforms 8. The second one also adopts the design of two bonding platforms 8, but a semicircular locking hole 11 is opened on one of them, and a complete circular locking hole 11 is opened on the other. The third design structure is coated with a coating on one of the bonding platforms 8, and the fourth is coated with a coating on all the bonding platforms 8. The coating can be made of silver or nickel. The fifth structure adopts the design of three bonding platforms 8, and semicircular locking holes 11 are opened on at least two of the bonding platforms 8. Of course, similar structures can also be designed when it is necessary to complete specific functions. The specific application will not go into too much detail.

[0031] In summary, in order to solve the problem of the bonding strength between the lead frame structure and the plastic encapsulation material, the present application adopts a cascade of multiple groups of lead frame structures, and designs an extrusion step on the basic unit in each lead frame structure. Due to the existence of the extrusion depth of the step, the bonding strength between the overall lead frame structure and the plastic encapsulation material can be significantly improved. In addition, the formation of elliptical through holes on the longitudinal connecting ribs of the cascade, and the provision of dovetail grooves and other structures on the base island can further improve the bonding strength of the plastic encapsulation material, thereby solving the problem of stratification between the frame and the plastic encapsulation material.

[0032] The preferred embodiments of the present invention are described above; it should be understood that the present invention is not limited to the above-mentioned specific implementation modes, and the devices and structures not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can make many possible changes and modifications without departing from the technical solution of the present invention, or modify them into equivalent embodiments with equivalent changes, which does not affect the essential content of the present invention; therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A lead frame structure for increasing bonding properties, characterized in that: The invention comprises a frame (1), wherein a plurality of groups of interconnected lead frame units are arranged in the frame (1), wherein the lead frame units contain a plurality of basic units (2) having the same structure and arranged in an array, wherein the lead frame units in adjacent columns are connected by longitudinal connecting ribs (4), and the basic units (2) in adjacent rows are connected by transverse connecting ribs (3); and an extrusion step (6) is arranged on the basic unit (2).

2. A lead frame structure for increasing bonding properties according to claim 1, characterized in that: A plurality of groups of circular and / or elliptical first through holes (101) are evenly provided on the frame (1), and the first through holes (101) correspond one-to-one to the lead frame units; and elliptical second through holes (41) are evenly provided on the longitudinal connecting rib (4).

3. A lead frame structure for increasing bonding properties according to claim 1, characterized in that: The basic unit (2) further comprises a dovetail groove (5) and a base island (7); the dovetail groove (5) is located above the base island (7), V-shaped grooves are arranged on both sides of the base island (7), and the extrusion steps (6) are symmetrically arranged on both sides of the dovetail groove (5).

4. A lead frame structure for increasing bonding properties according to claim 3, characterized in that: The depth of the dovetail groove (5) is 0.25 to 0.40 times of the thickness, and the width is 0.30 to 0.40 mm.

5. The lead frame structure for increasing bonding properties according to claim 3, characterized in that: A heat sink is arranged on the back of the base island (7), and the extrusion steps (6) are symmetrically arranged on both sides of the heat sink. The depth of the extrusion steps (6) is 0.10 to 0.30 times the thickness.

6. A lead frame structure for increasing bonding properties according to claim 5, characterized in that: The basic unit (2) further comprises a bonding platform (8) and a stamp (10), wherein the bonding platform (8) and the stamp (10) are connected via a pin (9).

7. A lead frame structure for increasing bonding properties according to claim 6, characterized in that: A material locking hole (11) is provided on the bonding platform (8), the material locking hole (11) is circular or semicircular, and the stamp (10) is configured to be square or rectangular.

8. A lead frame structure for increasing bonding properties according to claim 7, characterized in that: The bonding platforms (8) are arranged in two or three parallel configurations.

9. A lead frame structure for increasing bonding properties according to claim 8, characterized in that: The surface of the bonding platform (8) is provided with a silver plating layer or a nickel plating layer.

10. A lead frame structure for increasing bonding properties according to claim 9, characterized in that: A plastic packaging material (12) is arranged outside the basic unit (2).

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