阅读说明：本技术 一种半导体封装件及其制造方法 (Semiconductor packaging piece and manufacturing method thereof ) 是由 戴建业 刘伟 韦仕贡 张彦秀 于 2020-07-29 设计创作，主要内容包括：本发明公开一种半导体封装件及其制造方法。该半导体封装件包括：半导体芯片,其表面设有多个外接端子；引线框架,其具有多个用于与外部电路连接的管脚；连接部,其包括作为连接线路的多条引线以及用于承载多条引线的绝缘基材层,其中引线的一端与外接端子连接,另一端与管脚连接；以及封装胶体,其包覆半导体芯片、引线框架和连接部,管脚暴露于封装胶体的外侧。本发明通过连接部上的引线连接半导体芯片的外接端子与引线框架外围的管脚,即利用连接部电连接代替了金属焊线电连接,从而省略了焊线工序,解决了金属焊线焊接不良所带来产品良率低的问题。(The invention discloses a semiconductor package and a manufacturing method thereof. The semiconductor package includes: a semiconductor chip having a plurality of external terminals on a surface thereof; a lead frame having a plurality of pins for connection with an external circuit; the connecting part comprises a plurality of leads serving as connecting lines and an insulating substrate layer used for bearing the leads, wherein one ends of the leads are connected with the external terminals, and the other ends of the leads are connected with the pins; and the packaging colloid covers the semiconductor chip, the lead frame and the connecting part, and the pins are exposed to the outer side of the packaging colloid. The lead on the connecting part is connected with the external terminal of the semiconductor chip and the peripheral pin of the lead frame, namely the connecting part is electrically connected to replace a metal welding wire, so that the welding wire process is omitted, and the problem of low product yield caused by poor welding of the metal welding wire is solved.)

1. A semiconductor package, comprising:

a semiconductor chip having a plurality of external terminals on a surface thereof;

a lead frame having a plurality of pins for connection with an external circuit;

the connecting part comprises a plurality of leads serving as connecting lines and an insulating substrate layer used for bearing the leads, wherein one ends of the leads are connected with the external terminals, and the other ends of the leads are connected with the pins; and

and the packaging colloid covers the semiconductor chip, the lead frame and the connecting part, and the pins are exposed to the outer side of the packaging colloid.

2. The semiconductor package of claim 1, wherein the insulating substrate layer has first and second opposing surfaces, wherein the first surface is proximate to the semiconductor chip and the second surface is proximate to the lead frame;

the leads comprise a first lead positioned on the first surface, a second lead positioned on the second surface and a connecting wire positioned in the insulating base material layer;

one end of the first lead is connected with an external terminal of the semiconductor chip, and the other end of the first lead is connected with the connecting wire; one end of the second lead is connected with the pin of the lead frame, and the other end of the second lead is connected with the connecting wire.

3. The semiconductor package of claim 1, wherein the insulating substrate layer has first and second opposing surfaces, wherein the first surface is proximate to the semiconductor chip and the second surface is proximate to the lead frame;

one end of the lead is exposed on the first surface and connected with an external terminal of the semiconductor chip, the other end of the lead is exposed on the second surface and connected with a pin of the lead frame, and the other part of the lead is positioned in the insulating base material layer.

4. The semiconductor package part according to claim 2 or 3, wherein the second surface of the insulating substrate layer is provided with an adhesive layer, and the insulating substrate layer is attached to the surface of the lead frame through the adhesive layer.

5. The semiconductor package according to any one of claims 1 to 3, wherein both ends of the lead are provided with pads for connection with an external terminal of the semiconductor chip and a pin of the lead frame, respectively.

6. The semiconductor package according to claim 5, wherein the surface of the pad protrudes from the surface of the insulating substrate layer.

7. The semiconductor package according to any one of claims 1 to 6, wherein the connection portion is a flexible circuit board.

8. A method for manufacturing a semiconductor package, comprising the steps of:

fixing a connecting part on the surface of a lead frame, wherein the connecting part comprises a plurality of leads serving as connecting lines and an insulating substrate layer for bearing the leads;

connecting one end of the lead with an external terminal of a semiconductor chip, and connecting the other end of the lead with a pin of the lead frame;

and encapsulating the semiconductor chip, the lead frame and the connecting part by using an encapsulating colloid, and at least exposing the pin of the lead frame.

9. The method of manufacturing according to claim 8, further comprising the step of fabricating the connection portion:

forming a plurality of leads in the insulating base material layer;

and a pad for connecting an external terminal is formed at one end of the lead, and a pad for connecting a pin is formed at the other end of the lead.

10. The manufacturing method according to claim 8 or 9, wherein the connecting portion is a flexible circuit board.

Technical Field

The invention relates to the field of semiconductor manufacturing, in particular to a semiconductor packaging piece and a manufacturing method thereof.

Background

In a conventional semiconductor package using a lead frame as a chip carrier, such as a Quad Flat Package (QFP) and a quad flat no-lead (QFN) semiconductor package, a semiconductor chip is bonded to a lead frame having a chip pad and a plurality of pins, an external terminal on the surface of the chip is electrically connected to the pins on the lead frame through a plurality of metal bonding wires, and finally the chip and the metal bonding wires are encapsulated by an encapsulant to form the semiconductor package.

As the market demand for consumer electronics performance continues to increase, higher demands are placed on the performance of semiconductor chips and semiconductor packages. Taking medium and high-end consumer electronic products as an example, in a QFN product used by the product, the number of pins around a lead frame is basically not less than 60, and the number of metal bonding wires is basically more than 100. In the actual packaging process, the bending and poor welding of the bonding wires in the wire bonding process are important factors that lead to low yield of QFN products, and the yield of the QFN products is lower as the number of the metal bonding wires increases.

Disclosure of Invention

The invention aims to provide a semiconductor packaging piece and a manufacturing method thereof, wherein the semiconductor packaging piece can avoid the bending of a welding wire, reduce the abnormal occurrence frequency of a welding spot and improve the long-term use reliability of the semiconductor packaging piece.

According to an aspect of the present invention, there is provided a semiconductor package including: a semiconductor chip having a plurality of external terminals on a surface thereof; a lead frame having a plurality of pins for connection with an external circuit; the connecting part comprises a plurality of leads serving as connecting lines and an insulating substrate layer used for bearing the leads, wherein one ends of the leads are connected with the external terminals, and the other ends of the leads are connected with the pins; and the packaging colloid covers the semiconductor chip, the lead frame and the connecting part, and the pins are exposed to the outer side of the packaging colloid.

Further, the insulating base material layer is provided with a first surface and a second surface which are opposite, wherein the first surface is close to the semiconductor chip, and the second surface is close to the lead frame; the leads comprise a first lead positioned on the first surface, a second lead positioned on the second surface and a connecting wire positioned in the insulating base material layer; one end of the first lead is connected with an external terminal of the semiconductor chip, and the other end of the first lead is connected with the connecting wire; one end of the second lead is connected with the pin of the lead frame, and the other end of the second lead is connected with the connecting wire.

Further, the insulating base material layer is provided with a first surface and a second surface which are opposite, wherein the first surface is close to the semiconductor chip, and the second surface is close to the lead frame; one end of the lead is exposed on the first surface and connected with an external terminal of the semiconductor chip, the other end of the lead is exposed on the second surface and connected with a pin of the lead frame, and the other part of the lead is positioned in the insulating base material layer.

Further, the connecting portion is provided with a positioning point for positioning with the semiconductor chip.

Furthermore, an insulating layer for wrapping the lead is arranged on the surface of the insulating base material layer.

Furthermore, the second surface of the insulating substrate layer is provided with an adhesive layer, and the insulating substrate layer is attached to the surface of the lead frame through the adhesive layer.

Further, both ends of the lead are provided with pads for connection with an external terminal of the semiconductor chip and a pin of the lead frame, respectively.

Further, the surface of the bonding pad protrudes out of the surface of the insulating base material layer.

Further, the surface of the bonding pad is plated with nickel or tin metal.

In the semiconductor package described above, the connection portion is a flexible circuit board.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor package, including the steps of: fixing a connecting part on the surface of the lead frame, wherein the connecting part comprises a plurality of leads serving as connecting lines and an insulating base material layer for bearing the leads; connecting one end of a lead with an external terminal of the semiconductor chip, and connecting the other end of the lead with a pin of the lead frame; and the semiconductor chip, the lead frame and the connecting part are coated by the packaging colloid, and at least the pins of the lead frame are exposed.

Further, the method also comprises the following steps of: forming a plurality of leads in the insulating base material layer; a pad for connecting an external terminal is formed at one end of the lead, and a pad for connecting a pin is formed at the other end of the lead.

Further, the connecting portion is a flexible circuit board.

The invention has the following beneficial effects:

the semiconductor packaging piece provided by the invention adopts the lead in the connecting part to connect the external terminal of the semiconductor chip and the pin of the lead frame, namely, the connecting part is electrically connected to replace the traditional metal welding wire, so that the welding wire process is omitted, and the problem of low product yield caused by poor welding of the welding wire and the metal welding wire is solved. In addition, the connecting part is adopted to replace metal welding wire for electric connection, so that the electric connection of the connecting part can be completed through mounting, reflow soldering and other processes in the processing process.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Fig. 1 shows a schematic structural diagram of a semiconductor package in an embodiment of the invention.

Fig. 2 is a schematic view showing a connection structure of a lead frame and a connection portion in the embodiment of the present invention.

Fig. 3 shows a cross-sectional view of a connection structure of the semiconductor chip, the connection portion, and the lead frame in the embodiment of the present invention.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

As shown in fig. 1 to 3, an embodiment of the present invention provides a semiconductor package similar to a QFN package structure, which includes: a semiconductor chip 10, a lead frame 20, a connection portion 30, and an encapsulant (not shown).

The surface of the semiconductor chip 10 is provided with a plurality of external connection terminals 11 (also referred to as PADs or PADs). Preferably, all the external terminals 11 of the semiconductor chip 10 are located on the same side of the semiconductor chip 10, so as to facilitate connection with the lead frame 20 through the connection portion 30, and further connection with an external circuit.

The lead frame 20 serves as a chip carrier of the integrated circuit, and functions as a bridge for connecting the semiconductor chip 10 with an external circuit. Specifically, the lead frame 20 includes a chip holder (not shown) for holding the semiconductor chip 10, and a plurality of pins 21 for connection with an external circuit are provided around the chip holder. The side of the leadframe 20 (or die pad) that is used for connection to the semiconductor die 10 is referred to as the "front side" and the other side is referred to as the "back side" as generally defined by the microelectronics industry.

The connection portion 30 includes an insulating substrate layer 31 and a plurality of leads 32, and both ends of the leads 32 are connected to the external connection terminal 11 and the pin 21, respectively.

The encapsulant is used to encapsulate the semiconductor chip 10, the lead frame 20 and the connecting portion 30, and serves to protect the semiconductor chip 10 therein from corrosion and oxidation. In order to facilitate connection with an external circuit, the pins 21 of the lead frame 20 are partially exposed from the encapsulant, for example, in a manner similar to a QFN package, and the pins 21 are exposed from the side and/or the back of the encapsulant. In an actual product, the back surface of the lead frame 20 is also exposed to the outside of the encapsulant to facilitate heat dissipation of the semiconductor package. In some products, the pins 21 and the back side of the lead frame 20 may also be soldered to a Printed Circuit Board (PCB).

In the conventional process, the lead frame 20 electrically connects the semiconductor chip 10 to an external circuit by means of a bonding material, such as a metal bonding wire, e.g., gold wire, aluminum wire, copper wire, etc., and a metal bump, etc., to form an electrical circuit. Specifically, the lead frame 20 is electrically connected to an external circuit through the pins 21 around the lead frame and the external terminals 11 of the semiconductor chip 10 mainly by means of metal bonding wires. However, during the packaging process, when the melted molding compound is filled into the product at a certain flow rate, it is difficult to avoid applying pressure to the metal bonding wires therein, which is commonly referred to in the industry as wire sweep. With the increasing requirements of the market on the performance of chips and semiconductor packages, the number of metal bonding wires is greatly increased, and meanwhile, the chips and semiconductor packages are developed towards miniaturization, so that the density of the metal bonding wires is higher and higher, the process difficulty of the bonding wire process is greatly improved, the production efficiency is greatly reduced, and the product yield is greatly reduced due to poor welding of the metal bonding wires, bending of the bonding wires and other reasons.

In the semiconductor package provided by the embodiment of the invention, the external terminal 11 of the semiconductor chip 10 is connected with the pins 21 on the periphery of the lead frame 20 through the leads 32 on the connecting portion 30, that is, the connecting portion 30 is used for electrical connection to replace metal bonding wire electrical connection, so that a bonding wire process is omitted, and the problems of poor welding of the metal bonding wire and reduction of product yield caused by punching and bending of the bonding wire are solved. Furthermore, in the manufacturing process, the electrical connection between the connection portion 30 and the lead frame 20 can be completed by mounting and reflow soldering, and practice proves that the manufacturing cycle can be effectively shortened and the manufacturing efficiency can be improved.

In the conventional process, the electrical connection (bonding) of the metal bonding wire is mainly completed by using bonding equipment and a bonding pin (a tooling fixture of the bonding wire process) under the action of specific environment (power, pressure, time and temperature). In the welding process, the problems of infirm welding points, insufficient welding and the like often occur. The above problems are difficult to find during operation and during electrical performance testing. However, in the long-term use process of the product, the welding is not firm, and the welding spot of the cold welding falls off, so that poor contact is caused, and finally the function of the product is lost or even the product fails.

In the invention, the connecting part 30 is adopted to replace the metal welding wire for electric connection, so that series problems of infirm welding, insufficient welding and the like of the metal welding wire are avoided, the long-term reliability of the semiconductor packaging part is improved, and the service life of the semiconductor packaging part is prolonged. In addition, because the connection portion 30 is used for electrical connection instead of metal bonding wire electrical connection, the insulating substrate layer 31 of the connection portion 30 can play a role in supporting, fixing and even protecting the lead 32, so that the impact resistance of the circuit and the connection point is greatly improved, which is particularly obvious in severe environments such as high temperature, high humidity and high pressure.

Specifically, the insulating substrate layer 31 of the connection portion 30 has a first surface and a second surface opposite to each other, wherein the first surface is close to (or facing) the semiconductor chip 10, and the second surface is close to the lead frame 20.

In one embodiment, the leads 32 include a first lead attached to the first surface of the insulating substrate layer 31, a second lead attached to the second surface, and a connecting wire located in the insulating substrate layer 31 and having two ends respectively connected to the first lead and the second lead. The first lead is connected to the external connection terminal 11 of the semiconductor chip 10, and the second lead is connected to the pin 21 of the lead frame 20.

In this embodiment, the specific formation manner of the first lead, the second lead, and the connecting wire is not particularly limited. In one implementation, the first lead and the second lead are attached to the surface of the insulating substrate layer 31, for example, two surfaces of the insulating substrate layer 31 may be respectively provided with a groove, and a metal wire is formed in the groove to serve as the first lead and the second lead. The connecting lines may be via holes penetrating through the surfaces of the two sides of the insulating substrate layer 31.

In another embodiment, the lead 32 is located inside the insulating substrate layer 31, and two ends of the lead 32 are located on the first surface and the second surface respectively; specifically, one end of the lead 32 is exposed to the first surface and connected to the external terminal 11 of the semiconductor chip 10, the other end of the lead 32 is exposed to the second surface and connected to the pin 21 of the lead frame 20, and the other part of the lead 32 is located inside the insulating base material layer 31. That is, one end of the lead 32 is exposed from the first surface of the insulating base material layer 31 and connected to the external connection terminal 11 of the semiconductor chip 10, and the other end of the lead 32 is exposed from the second surface and connected to the pin 21 of the lead frame 20. The lead 32 is arranged inside the insulating base material layer 31, so that the insulating base material layer 31 can play a better role in supporting, fixing and protecting the lead 32, and the reliability of the semiconductor packaging piece is improved.

As shown in fig. 2, the connecting portion 30 is provided with positioning points 33, and the positioning points 33 may be identification points formed on the first surface of the insulating substrate layer 31, or may also be positioning holes located in the insulating substrate layer 31. When the semiconductor chip 10 is placed over the connection portion 30, the grasping mechanism can accurately place the semiconductor chip 10 on the first surface of the insulating substrate layer 31 through the positioning points 33, so that the external connection terminals 11 of the semiconductor chip 10 are in contact with the ends of the leads 32 of the connection portion 30, and the two are conveniently soldered. Specifically, the number of the positioning points 33 is four, and the positioning points are respectively arranged at four corners of the central rectangular region of the insulating base material layer 31. The shape of the anchor point 33 may be circular, square, cross-shaped, etc.

In one embodiment, the surface of the connecting portion 30 is further provided with an insulating layer, and the insulating layer is coated on the first surface and the second surface of the insulating substrate layer 31, so that the lead 32 is effectively covered to protect the lead 32, and the lead 32 is isolated from external dust and moisture. Further, in some products with specific requirements, an electromagnetic shielding film EMI may be further disposed on the surface of the insulating layer to protect the lead 32 from strong electromagnetic interference from the outside.

In one embodiment, an adhesive layer is further disposed between the second surface of the insulating substrate layer 31 and the front surface of the lead frame 20, and the insulating substrate layer 31 is attached to the surface of the lead frame 20 through the adhesive layer. The surface of the lead frame 20 protrudes to form a plurality of positioning columns, the insulating base material layer 31 is provided with positioning holes corresponding to the positioning columns, accurate positioning between the connecting portion 30 and the lead frame 20 can be achieved through matching of the positioning holes and the positioning columns, and the end portions of the leads 32 are ensured to be fully contacted with the pins 21 of the lead frame 20, so that effective connection between the two portions is facilitated.

In this embodiment, how to realize the electrical connection between the lead 32 and the pin 21, and between the lead 32 and the external terminal 11 are not particularly limited, and a conventional electrical connection method in the semiconductor field may be adopted. As shown in fig. 2 and 3, both ends of the lead 32 are provided with pads 34 for soldering with the external connection terminal 11 of the semiconductor chip 10 and the pin 21 of the lead frame 20, respectively. A bump 12 is formed on the external terminal 11 of the semiconductor chip 10 by using a Bumping process, and serves as a connection point for conducting the semiconductor chip 10 to the outside, and a dome-shaped or hemispherical metal tin is provided on the top of the bump 12 for facilitating the soldering with the pad 34.

In one embodiment, the surface of the pad 34 protrudes from the surface of the insulating substrate layer 31, that is, the pads 34 at two ends of the lead 32 are higher than the surface of the insulating substrate layer 31, so as to facilitate the soldering of the pads 34 with the external connection terminal 11 and the pin 21, respectively. Preferably, the surface of the pad 34 is plated with metallic nickel or tin to facilitate soldering.

In a preferred embodiment, the connection portion 30 is a circuit board, and particularly, a flexible circuit board FPC may be selected. The basic structure of the flexible circuit board is a copper foil substrate, a substrate film of the flexible circuit board is an insulating substrate layer 31 which is mainly made of polyimide or polyester, and copper foil in the flexible circuit board is formed into a lead 32.

Since the flexible circuit board has good elasticity, the flexible circuit board is used as the connecting portion 30, and the circuit conduction is not affected under the action of external stress. And secondly, the thickness of the flexible circuit board can be controlled to be less than 100 microns, so that the occupied space can be greatly reduced, the miniaturization of the semiconductor packaging piece is favorably realized, and a larger design freedom degree is provided for the structural design of a product.

The invention also discloses a manufacturing method of the semiconductor packaging piece, and with reference to fig. 1 to 3, the manufacturing method comprises the following steps:

fixing a connecting part 30 on the surface of the lead frame 20, wherein the connecting part 30 comprises a plurality of leads 32 serving as connecting lines and an insulating substrate layer 31 for bearing the leads 32;

one end of the lead 32 is connected to the external terminal 11 of the semiconductor chip, and the other end of the lead 32 is connected to the pin 21 of the lead frame;

the semiconductor chip 10, the lead frame 20 and the connecting portion 30 are covered with an encapsulant, and at least the pins 21 of the lead frame 20 are exposed.

In one embodiment, the method further comprises the following steps:

chip grinding and scribing: according to the product requirements, the processed wafer grinding plate is thinned to the required thickness, and then the thinned wafer is cut into single chips (die), namely the semiconductor chip 10.

Film pasting on the back: a protective film is attached to the back surface of the lead frame 20 to prevent glue from overflowing in the subsequent plastic packaging process (according to the process design, this step may be placed in a step before the plastic packaging process).

The connecting part 30 is mounted: the lead frame 20 is fixed on the carrier, so that the lead frame 20 is prevented from warping in the subsequent operation process, the surface of the insulating base material layer 31 is coated with the adhesive, and the connecting part 30 is attached to the surface of the lead frame 20 through the adhesive.

Chip mounting: the semiconductor chip 10 is mounted on the other surface of the connection portion 30, and the external connection terminal 11 of the semiconductor chip 10 is electrically connected to the pad 34 at the end of the lead 32. Preferably, the connection portion 30 is provided with an alignment point 33, and the semiconductor chip 10 can be accurately aligned with the connection portion 30 through the alignment point 33, so that the effective connection between the external connection terminal 11 and the lead 32 is realized.

This step may also be referred to as Flip Chip bonding, which belongs to Flip Chip bonding (Flip Chip), and in the specific implementation process, the electrical connection between the semiconductor Chip 10 and the connection portion 30 may be realized by means of a metal bump, a flux, and a Flip Chip bonding device. Of course, other means are not excluded as long as the electrical connection between the external connection terminal 11 of the semiconductor chip 10 and the lead 32 of the connection portion 30 can be achieved.

Reflow soldering: the pads 34 on the second surface of the connecting portion 30 are connected to the pins 21 of the lead frame 20, so as to electrically connect the external terminals 11 of the semiconductor chip 10 and the pins 21 of the lead frame 20.

In the specific implementation of this step, the reflow device may be used to melt and solidify the metal between the bonding pad 34 on the second surface of the connecting portion 30 and the pin 21 of the lead frame 20, so as to form a bonding pad.

Washing with water: and residues left during welding are cleaned by a washing machine, so that the reliability of plastic packaging is ensured.

Plastic packaging: the melted encapsulant is wrapped around the front surfaces of the semiconductor chip 10, the connecting portion 30 and the lead frame 20 by an encapsulation machine and cured.

The appearance of the semiconductor product after plastic packaging is similar to that of the traditional QFN packaging product, and the back of the lead frame 20 is exposed to the outside to facilitate heat dissipation; the pins 21 on the lead frame 20 are partially exposed to facilitate electrical connection with an external circuit.

In one embodiment, the method further includes a ball-mounting process, in which solder balls are fixed on the back surface of the lead frame 20 by using a ball-mounting device, and then high-temperature curing is performed by reflow soldering.

Further, a step of preparing the connection part 20 may be further included. Taking the flexible circuit board as an example, the circuit design can be performed first: according to the position of the external terminal 11 of the semiconductor chip 10 and the position of the lead frame pin 21, a matching connection pattern and a connection circuit are designed by CAD/CAM software; then, designing a metal bump connection end point: the pads 34 of the flexible circuit board are designed according to the material composition of the surface of the metal bumps 12 on the semiconductor chip 10. For example, the metal bump 12 on the chip is a copper pillar main body, and the surface semicircle is nickel and tin, so the material of the flexible circuit board pad 34 is generally tin alloy, and of course, other metal materials can be used according to the product characteristics; finally, designing the connection end point with the pin 21: the bonding pads 34 of the flexible circuit board are designed according to the composition of the plating material of the pins 21 on the lead frame 20, and the material is generally tin alloy, and other metal materials can be adopted according to the product characteristics.

The flexible circuit board in the embodiment generally only needs to be manufactured by a single panel, and the existing mature manufacturing process can be adopted. It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.