CN216563112U

CN216563112U - Lead frame unit, lead frame and packaging body

Info

Publication number: CN216563112U
Application number: CN202122858112.9U
Authority: CN
Inventors: 胥益; 杨超; 刘俊; 舒蕃
Original assignee: Chengdu Perfect Technology Co ltd
Current assignee: Chengdu Perfect Technology Co ltd
Priority date: 2021-11-19
Filing date: 2021-11-19
Publication date: 2022-05-17
Anticipated expiration: 2031-11-19

Abstract

Disclosed are a lead frame unit, a lead frame and a package body, the lead frame unit including: a heat sink; one end of the chip carrying table is connected with the radiating fin, the chip carrying table comprises a first surface and a second surface which are opposite, and a chip is arranged on the first surface; the pins are connected with the other end of the slide holder; the first surface is provided with an enclosing structure, and the enclosing structure is annular and is positioned on the periphery of the chip and surrounds the chip. According to the utility model, the wafer carrying table is provided with the enclosure structure, so that the problems of overflow of solder and non-uniform thickness in the prior art can be solved.

Description

Lead frame unit, lead frame and packaging body

Technical Field

The utility model relates to the technical field of semiconductors, in particular to a lead frame unit, a lead frame and a packaging body.

Background

The lead frame is used as a chip carrier of semiconductor packaging of discrete devices, the electrical connection between a chip internal circuit and a leading-out terminal of the lead frame is realized by means of a bonding wire, the lead frame is a key structural member for forming an electrical circuit, plays a role in circuit connection and chip fixation, and is an important basic material in the electronic information industry.

In the packaging process of the discrete device semiconductor, molten soft solder needs to be melted and then is placed on the surface of a wafer carrying table of a lead frame, then a chip is placed on the soft solder, the electric connection function of the chip and the lead frame is realized, and the thickness of the soft solder under the chip and the uniformity and stability of the soft solder are main indexes for considering the soft solder to bond the chip. Because the molten soft solder is semicircular or spherical and has fluidity, the thickness of the soft solder is difficult to control, the uniformity is poor, and the difference of the thermal conductivity and the electrical conductivity of the packaged product is easily caused. Meanwhile, soft solder is used as a buffer medium between the lead frame and the chip, and if the thickness of the soft solder is insufficient or uneven, chip cracks or a layering phenomenon between a soft solder layer and a chip carrying table of the lead frame is easily caused, so that the reliability of the product is reduced.

The wafer carrying table of the lead frame of the traditional discrete device is mainly designed in a full plane or in a design with an anti-overflow groove; when the slide holder adopts a full-plane design, soft solder points flow along the surface of the lead frame after the surface of the lead frame and overflow to the back of the lead frame, so that the product is poor; when the slide holder adopts the design of taking the anti-overflow groove, though the existence of anti-overflow groove has blockked the excessive of soft solder, nevertheless along with spilling over of soft solder, the thickness and the homogeneity of soft solder all receive the influence under the chip, and product reliability can't guarantee.

SUMMERY OF THE UTILITY MODEL

In view of the above problems, an object of the present invention is to provide a lead frame unit, a lead frame and a package body, so as to solve the problems of solder overflow and uneven thickness in the prior art.

The present invention provides a lead frame unit, including:

a heat sink;

one end of the chip carrying table is connected with the radiating fin, the chip carrying table comprises a first surface and a second surface which are opposite, and a chip is arranged on the first surface;

the pins are connected with the other end of the slide holder;

the first surface is provided with an enclosing structure, and the enclosing structure is annular and is positioned on the periphery of the chip and surrounds the chip.

Preferably, the enclosure structure protrudes from the first surface of the slide holder in a direction away from the first surface.

Preferably, the enclosure structure is rectangular ring-shaped.

Preferably, a plurality of grooves are formed in the outer wall of the enclosure structure.

Preferably, the shape of the groove is any one or a combination of a plurality of arc-shaped grooves, triangular grooves, rectangular grooves and trapezoidal grooves.

Preferably, the depth of the groove is up to half of the width of the enclosure structure.

Preferably, the height of the enclosure structure is 0.1 mm-0.3 mm, and the width of the enclosure structure is 0.3 mm-0.5 mm.

Preferably, the enclosure structure is arranged at the edge of the first surface of the slide holder.

Preferably, the distance between the outer wall of the enclosure structure and the outer wall of the slide holder is 0.3 mm-1 mm.

Preferably, the outer wall of the slide holder is provided with a step part.

Preferably, at least one of the plurality of pins is connected to the stage.

Preferably, the pins are bent at the connection part with the slide holder, and a height drop exists between the slide holder and the plane where the pins are located.

Preferably, the pin is provided with a pin cutting mark, and the width of the pin at the pin cutting mark is smaller than that of the rest area of the pin.

Preferably, the heat sink is provided with a mounting hole for mounting and fixing an external heat sink.

The present invention provides a lead frame, comprising:

at least one of the above lead frame units; and

and the radiating fins of the adjacent lead frame units are connected into a whole through the connecting ribs.

Preferably, the lead frame further comprises a frame, and the frame connects the plurality of pins of the plurality of lead frame units and the pins of the adjacent lead frame units into a whole.

The present invention provides a package, comprising:

at least one of the above lead frame units;

the chip is attached to the chip carrying table of the lead frame unit; and

and the plastic package body is plastically packaged outside the lead frame unit and covers the chip carrier and the chip.

In the lead frame unit provided by the utility model, the wafer carrying table is provided with the enclosing structure which encloses the chip, on one hand, the enclosing structure is used as a wall body to enclose the solder, so that the solder is prevented from overflowing, and the solder is prevented from flowing to the second surface of the wafer carrying table, the radiating fin and the plurality of pins, so that the product is poor; on the other hand, the solder is surrounded by the surrounding structure and evenly paved on the wafer carrying table, so that the uniformity and the stability of the thickness of the solder are ensured.

Furthermore, the outer wall of the enclosure structure is provided with a groove, the groove increases the contact area with the plastic package body, the stability and the reliability between the enclosure structure and the plastic package body are improved, and the bonding strength between the lead frame unit and the plastic package body is further improved; meanwhile, the enclosing structure separates the solder from the plastic package body, and after packaging, the enclosing structure can prevent external water vapor from entering the region limited by the enclosing structure, so that layering among the slide holder, the solder and the chip can be avoided.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

fig. 1 is a schematic structural diagram of a lead frame provided by an embodiment of the utility model;

FIG. 2 shows a cross-sectional view along AA of FIG. 1;

FIG. 3 shows an enlarged view at B in FIG. 1;

fig. 4 shows a side view of a lead frame of an embodiment of the present invention.

Detailed Description

To facilitate an understanding of the utility model, the utility model will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. The utility model may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model.

The present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a lead frame provided by an embodiment of the utility model; FIG. 2 shows a cross-sectional view along AA of FIG. 1; FIG. 3 shows an enlarged view at B in FIG. 1; referring to fig. 1, 2 and 3, the lead frame provided by the present invention includes a plurality of lead frame units 10 arranged in sequence, and the lead frame units 10 are connected to each other by connecting ribs 14.

The lead frame unit 10 includes: the heat dissipation plate comprises a heat dissipation plate 11, a slide holder 12, a plurality of pins 13 and a surrounding structure 15, wherein the heat dissipation plate 11 and the plurality of pins 13 are positioned on two opposite side edges of the slide holder 12; the heat sink 11 is connected with one end of the stage 12, one surface of the stage 12 is used for mounting a chip, the pins 13 are disposed at the other end of the stage 12 and serve as lead-out terminals of the lead frame, optionally, the pins 13 are arranged in parallel, and the joints between the pins 13 and the stage 12 are designed to be bent. The heat sinks 11 of the adjacent lead frame units 10 are integrally connected through the connecting ribs 14.

Two opposite surfaces (a first surface 121 and a second surface 122) of the stage 12 are both flat surfaces, the first surface 121 of the stage 12 is used for mounting a chip, the enclosure structure 15 is located on the first surface 121 of the stage 12, and extends from the first surface 121 to a direction away from the first surface 121 and the second surface 122 to form a circle of enclosure structures 15 protruding relative to the first surface 121, and the enclosure structures 15 are annular and located on the periphery of the chip and surround the chip.

In the process of attaching the chip to the stage 12, the solder needs to be melted and then spotted on the stage 12, and then the chip is placed on the solder to realize the electrical connection between the chip and the lead frame unit 10; in this process, the melted solder dots flow behind the stage 12.

In this embodiment, the enclosure structure 15 is disposed at an edge of the first surface 121 of the stage 12, and an outer wall of the enclosure structure 15 has a certain distance from an outer wall of the stage 12. In this embodiment, for example, the distance d between the outer wall of the enclosure structure 15 and the outer wall of the slide holder 12 is 0.3mm to 1 mm.

The inner wall of the enclosure structure 15 defines the area of the chip mounting table 12, and the melted solder points are in the area defined by the inner wall of the enclosure structure 15, on one hand, the enclosure structure 15 protruding relative to the first surface 121 acts as a wall to enclose the solder, so as to prevent the solder from overflowing, and prevent the solder from flowing to the second surface 122 opposite to the first surface 121, the heat sink 11 and the plurality of pins 13, which results in poor product; on the other hand, the solder is surrounded by the surrounding structure 15 and evenly spread on the wafer carrying table 12, so that the uniformity and the stability of the thickness of the solder are ensured.

At least one chip is mounted on each slide holder 12, and the number of the mounted chips can be designed according to actual requirements. The area and shape of the defined area of the dam structure 15 corresponds to the type and number of chips. In the preferred embodiment of the present invention, the slide holder 12 is designed to mount a chip, the chip is rectangular, and accordingly, the enclosure structure 15 is rectangular and annular, and the area defined by the enclosure structure 15 is rectangular.

Referring to fig. 1 and 3, a plurality of grooves 151 are disposed on an outer wall of the enclosure structure 15. In the process of packaging the stage 12, a liquid plastic package (for example, epoxy resin) is filled outside the stage 12 and cured; the plastic-sealed body and slide holder 12 and enclose fender structure 15 contact, enclose recess 151 on the fender structure 15 outer wall and increased with the area of contact of the plastic-sealed body, increased enclose stability and reliability between fender structure 15 and the plastic-sealed body, and then increased the bonding strength of lead frame unit and plastic-sealed body. Meanwhile, the enclosing structure 15 separates the solder from the plastic package body, and after packaging, the enclosing structure 15 can prevent external water vapor from entering the region defined by the enclosing structure 15, so that the chip carrying table 12, the solder and the chip are prevented from being layered.

In a preferred embodiment of the present invention, the groove 151 is an arc groove, it is understood that the groove 151 may also be one or a combination of any number of triangular, rectangular, and trapezoidal grooves, the shape of the groove 151 is not limited by the present invention, and a person skilled in the art may set the shape of the groove 151 as needed, and at the same time, a person skilled in the art may set the number of the grooves 151 as needed.

The enclosure structure 15 has a certain height and width, and in a preferred embodiment of the present invention, referring to fig. 2, the height H of the enclosure structure 15 is 0.1mm to 0.3mm, the width W is 0.3mm to 0.5mm, preferably the height is 0.15mm, and preferably the width is 0.4 mm. Referring to fig. 3, the depth h of the groove 151 is up to half the width W of the dam structure 15.

With continued reference to fig. 1 and 2, the outer wall of the stage 12 is provided with a step portion 123, and the step portion 123 is located on two side walls of the stage 12, which are not connected to the heat sink 11 and the plurality of pins 13. Through setting up step portion 123 has increased with the area of contact of plastic-sealed body, has increased stability and reliability between slide holder 12 and the plastic-sealed body, and then has increased the bonding strength of lead frame unit and plastic-sealed body.

In this embodiment, along the thickness direction of the slide holder 12, the step portion 123 is a one-step, and may also be set as a multi-step, so as to further increase the contact area with the plastic package body.

In other embodiments, the step portion 123 can be replaced by other structures, such as a concave or convex structure disposed on the sidewall of the stage 12.

With continued reference to fig. 1, at least one of the plurality of pins 13 is connected to the stage 12, making the lead frame unit 10 as a unitary structure. In this embodiment, three pins 13 are included, and in other embodiments, a person skilled in the art may arbitrarily set the number of the pins 13 according to needs, and this embodiment does not limit the number of the pins 13.

Each pin 13 is provided with a pin cutting mark 131, the width of the pin 13 at the pin cutting mark 131 is smaller than the width of the rest area of the pin 13, the design is convenient for adapting to the pin length requirements of different lead frames in the design stage, and the required pin length can be directly cut in the packaging stage without secondary operation.

Fig. 4 shows a side view of the lead frame of the embodiment of the utility model, as shown in fig. 4, the pins 13 are bent at the connection with the stage 12, and the stage 12 has a height difference from the plane of the pins 13.

Furthermore, a frame 16 is disposed on the periphery of the pins 13, and the frame 16 integrally connects the pins 13 of the lead frame units 10 and the pins 13 of the adjacent lead frame units 10.

Further, the heat sink 11 is further provided with a mounting hole 111 for facilitating mounting and fixing of an external heat sink. The heat sinks 11 of the adjacent lead frame units 10 are integrally connected through the connecting ribs 14.

The lead frame units 10 are isolated from each other and are connected only by the connecting ribs 14 and a portion of the frame 16, so that in the preferred embodiment of the present invention, the lead frame is a unitary structure.

Further, the lead frame is an integrated structure formed by, for example, a strip-shaped substrate of a conductive material, for example, copper or aluminum, after an excess portion is removed by stamping or etching. The peripheral structure of the lead frame unit 10 is the frame 16, and the frame 16 is cut into ribs and removed after the package of the lead frame unit 10 is completed.

The package provided by the utility model comprises the lead frame unit 10, a chip and a plastic package body. The chip is attached to the slide holder 12 of the lead frame unit 10; the plastic package body is plastically packaged outside the lead frame unit 10, and the plastic package body covers the chip carrier 12 and the chip.

In accordance with the embodiments of the present invention as set forth above, these embodiments are not exhaustive and do not limit the utility model to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the utility model and the practical application, to thereby enable others skilled in the art to best utilize the utility model and various embodiments with various modifications as are suited to the particular use contemplated. The utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A lead frame unit, characterized in that the lead frame unit comprises:

a heat sink;

the chip carrying platform comprises a first surface and a second surface which are opposite, and a chip is arranged on the first surface;

the pins are connected with the other end of the slide holder;

2. The lead frame unit of claim 1, wherein the dam structure protrudes from the first surface of the stage in a direction away from the first surface.

3. The lead frame unit of claim 1, wherein the dam structure is rectangular ring shaped.

4. The lead frame unit of claim 1, wherein the enclosure structure has a plurality of grooves formed in an outer wall thereof.

5. The lead frame unit according to claim 4, wherein the shape of the groove is any one or a combination of a plurality of circular arc-shaped grooves, triangular grooves, rectangular grooves and trapezoidal grooves.

6. Lead frame unit according to claim 4, characterized in that the depth of the recess amounts to half the width of the dam structure.

7. The lead frame unit according to claim 1, characterized in that the height of the dam structure is 0.1mm to 0.3mm and the width of the dam structure is 0.3mm to 0.5 mm.

8. The lead frame unit of claim 1, wherein the dam structure is disposed at an edge of the first surface of the stage.

9. The lead frame unit of claim 1, wherein the enclosure structure has an outer wall that is spaced from an outer wall of the stage by a distance of 0.3mm to 1 mm.

10. Lead frame unit according to claim 1, characterized in that the outer wall of the stage is provided with a step.

11. The lead frame unit of claim 1, wherein at least one of the plurality of pins is connected to a stage.

12. The lead frame unit of claim 1, wherein the pins are bent at a connection with the stage, the stage having a height drop from a plane in which the pins lie.

13. Lead frame unit according to claim 1, characterized in that the pins are provided with cut-off markings, the width of the pins at the cut-off markings being smaller than the width of the remaining area of the pins.

14. The lead frame unit of claim 1, wherein the heat sink has mounting holes disposed therein for mounting and securing an external heat sink.

15. A lead frame, comprising:

at least one lead frame unit according to any one of claims 1 to 14; and

16. The lead frame of claim 15, further comprising a frame connecting the plurality of pins of the plurality of lead frame units and the pins of adjacent lead frame units together.

17. A package, comprising:

at least one lead frame unit according to any one of claims 1 to 14;

the chip is attached to the chip carrying table of the lead frame unit; and