阅读说明：本技术 一种芯片的封装方法 (Chip packaging method ) 是由 顾俊晔 付贵平 胡健 于 2020-07-15 设计创作，主要内容包括：本发明涉及一种芯片的封装方法及结构,包括：采用一种基材,在基材上电铸金属管脚模块及线路；芯片背面通过高分子粘接材料与基材表面预设位置粘接；芯片正面的感应区外露；在芯片封装前,芯片表面预先覆盖了光刻胶或其他高分子材料；通过注塑模具注塑树脂将芯片、金属管脚模块、线路、引线包封在树脂包封层内；将基材移除,使管脚地面外露在包封层的下表面；通过机械研磨的方式打磨包封层上表面芯片正面的光刻胶或其他高分子材料外露；或者用注塑模具在注塑成形时,使注塑树脂不能注塑到高分子材料表面；采用化学药水或物理外力去除芯片表面外露的光刻胶或其他高分子材料；芯片正面高度低于包封层表面。此方法降低了半导体芯片的封装体厚度。(The invention relates to a chip packaging method and a structure, comprising the following steps: a base material is adopted, and metal pin modules and circuits are electroformed on the base material; the back surface of the chip is bonded with the preset position on the surface of the base material through a high-molecular bonding material; the induction area on the front surface of the chip is exposed; before packaging the chip, the surface of the chip is covered with photoresist or other high molecular materials in advance; encapsulating the chip, the metal pin module, the circuit and the lead in a resin encapsulating layer by injecting resin through an injection mold; removing the substrate to expose the ground of the pins on the lower surface of the encapsulating layer; polishing the photoresist or other high polymer materials on the front surface of the chip on the upper surface of the encapsulating layer in a mechanical grinding mode to expose; or when an injection mold is used for injection molding, the injection molding resin can not be injected to the surface of the high polymer material; removing the exposed photoresist or other high polymer materials on the surface of the chip by using chemical liquid medicine or physical external force; the height of the front surface of the chip is lower than that of the surface of the packaging layer. The method reduces the package thickness of the semiconductor chip.)

1. A method for packaging a chip is characterized by comprising the following steps:

adopting a base material, and electroforming a metal pin module on the base material, or electroforming the metal pin module and a metal bonding pad on the base material;

before the chip is packaged, a high polymer material covers the front sensing area of the chip to protect the chip;

the back surface of the chip is adhered to a preset position on the surface of the base material or a metal bonding pad through a high-molecular adhesive material;

connecting a bonding pad on the surface of the chip with the metal pin module in a lead bonding mode;

when the chip is packaged, resin is injected through an injection mold to encapsulate the chip, the metal pin module, the lead, the high polymer bonding material on the back of the chip and the high polymer material in the front sensing area of the chip in the resin, and an encapsulating layer is formed; or when an injection mold is used for injection molding, the upper surface of the mold cavity is directly contacted with the high polymer material of the functional area on the front side of the chip, so that the injection molding resin cannot be injected to the surface of the high polymer material, after the encapsulating layer is formed, the high polymer material on the chip is directly exposed out of the encapsulating layer, and at the moment, the mechanical grinding process is skipped;

physically removing the base material through manual work or equipment to expose the lower surface of the metal pin module;

When the high polymer material on the chip is not exposed out of the encapsulating layer, polishing the upper surface of the encapsulating layer in a mechanical grinding mode until the required thickness is reached, and meanwhile, the high polymer material on the front surface of the chip is exposed, but the lead is embedded into the encapsulating layer;

chemical liquid medicine or physical external force is adopted to remove the exposed high polymer material on the surface of the chip, so that the sensing area on the front surface of the packaged finished product chip is exposed, and meanwhile, the packaging layer wraps the part, which does not need to be exposed, around the chip.

2. The method of claim 1, wherein the substrate has a thickness of 150 μm.

3. The method for packaging a chip as claimed in claim 1, wherein the metal pin module has mushroom-head structure at its edge.

4. The method for packaging a chip according to claim 1, wherein the metal pin module is made of any one of gold, nickel, silver, copper, palladium and tin, or is formed by stacking more than one of gold, nickel, silver, copper, palladium and tin.

5. The method of claim 1, wherein the thickness of the metal pin modules and pads on the substrate is 40-65 μm.

6. The method for packaging a chip as claimed in claim 1, wherein the front surface of the chip is pre-coated with a polymer material, and the polymer material in the sensing region of the front surface of the chip is remained by exposure and development.

7. The method of claim 1, wherein after removing the polymer material of the front side sensing region, the height of the front side sensing region is lower than the upper surface of the encapsulating layer, thereby forming a recessed "patio structure".

8. The method of claim 1, wherein the upper surface of the encapsulation layer is polished to a thickness of 200 μm or less; or the height of the mold cavity of the injection mold is less than or equal to 200 microns during injection molding.

9. The method for packaging a chip of claim 1, wherein the chemical solution is an acidic solution, an alkaline solution, or a neutral solution, and the chemical solution cannot damage the sensing region on the front surface of the chip during the process of removing the exposed polymer material on the surface of the chip.

10. The method for packaging a chip according to claim 1, wherein the wire in the wire bonding manner is a metal wire, and the metal wire is a gold, copper, silver, aluminum, palladium or alloy wire.

Technical Field

The invention relates to a packaging method of a chip (especially an optical chip), belonging to the technical field of semiconductors.

Background

With the development of consumer electronics, the requirements of terminals for the space size of products are smaller and thinner, and the integration level is higher and higher. For example: a quad Flat no-Lead Package (QFN), a QFN structure generally includes a Lead frame with chip pads and Lead pins running, an encapsulating layer of plastic encapsulation resin, metal leads, and a chip. Due to the structure of the lead frame and the limitation of the packaging process, the thickness of the packaging encapsulation layer is about 450 microns at least.

In the traditional fingerprint chip packaging process, in order to expose the surface induction area of the chip, a special-shaped injection mold is needed in the injection molding packaging process, and the defects that the mold cost is high and different special-shaped injection molds are needed for different chip designs are overcome. This results in a great packaging cost and a very low operational flexibility.

In the existing packaging method, a chip is attached to a substrate, and a chip bonding pad is directly connected with a base pin of the substrate through wire bonding to realize electrical connection. Although the packaging thickness can be about 250 micrometers, the chip is exposed in the environment, the reliability cannot meet the requirement, and the operability in the packaging process is extremely low. The chip can meet the third grade of military standard by adopting the existing copper frame for packaging, but the packaging thickness is about 450 microns, and ultra-thin packaging cannot be realized. Meanwhile, during packaging, in order to expose the front surface of the chip on the packaging layer, a special-shaped plastic package mold is adopted for packaging. The special-shaped die is high in cost and extremely low in flexibility, so that the special-shaped die is not suitable for the field of consumer electronic chip packaging.

Disclosure of Invention

The purpose of the invention is: the thickness of the semiconductor packaging structure and the difficulty of the packaging process are reduced.

In order to achieve the above object, the present invention provides a chip packaging method, which includes the following steps:

adopting a base material, and electroforming a metal pin module on the base material, or electroforming the metal pin module and a metal bonding pad on the base material;

before the chip is packaged, a high polymer material covers the front sensing area of the chip to protect the chip;

the back surface of the chip is adhered to a preset position on the surface of the base material or a metal bonding pad through a high-molecular adhesive material;

connecting a bonding pad on the surface of the chip with the metal pin module in a lead bonding mode;

when the chip is packaged, resin is injected through an injection mold to encapsulate the chip, the metal pin module, the lead, the high polymer bonding material on the back of the chip and the high polymer material in the front sensing area of the chip in the resin, and an encapsulating layer is formed; or when an injection mold is used for injection molding, the upper surface of the mold cavity is directly contacted with the high polymer material of the functional area on the front side of the chip, so that the injection molding resin cannot be injected to the surface of the high polymer material, after the encapsulating layer is formed, the high polymer material on the chip is directly exposed out of the encapsulating layer, and at the moment, the mechanical grinding process is skipped;

Physically removing the base material through manual work or equipment to expose the lower surface of the metal pin module;

when the high polymer material on the chip is not exposed out of the encapsulating layer, polishing the upper surface of the encapsulating layer in a mechanical grinding mode until the required thickness is reached, and meanwhile, the high polymer material on the front surface of the chip is exposed, but the lead is embedded into the encapsulating layer;

chemical liquid medicine or physical external force is adopted to remove the exposed high polymer material on the surface of the chip, so that the sensing area on the front surface of the packaged finished product chip is exposed, and meanwhile, the packaging layer wraps the part, which does not need to be exposed, around the chip.

Preferably, the substrate has a thickness of 150 microns.

Preferably, the metal pin module edge has a mushroom head structure.

Preferably, the metal pin module is made of any one of gold, nickel, silver, copper, palladium and tin, or is formed by stacking more than one of gold, nickel, silver, copper, palladium and tin.

Preferably, the thickness of the metal pin module and the bonding pad on the base material is 40-65 microns.

Preferably, the front surface of the chip is covered with a polymer material in advance, and the polymer material in the sensing area on the front surface of the chip is reserved through exposure and development.

Preferably, after the polymer material of the chip front surface sensing area is removed, the surface height of the chip front surface sensing area is lower than that of the upper surface of the encapsulating layer, so that a groove 'patio structure' is formed.

Preferably, polishing the upper surface of the encapsulating layer to a thickness of less than or equal to 200 microns; or the height of the mold cavity of the injection mold is less than or equal to 200 microns during injection molding.

Preferably, the chemical liquid medicine is acidic liquid medicine, alkaline liquid medicine or neutral liquid medicine, and the chemical liquid medicine cannot damage the sensing area on the front surface of the chip in the process of removing the exposed high polymer material on the surface of the chip.

Preferably, the wire in the wire bonding manner is a metal wire, and the metal wire is a gold, copper, silver, aluminum, palladium or alloy wire.

The invention can lead the thickness of the packaging body to be less than or equal to 200 microns and simultaneously meet the requirement of high reliability. The chip, the lead, the metal pin module, the metal bonding pad and the photoresist or other high polymer materials in the front sensing area of the chip and the high polymer bonding materials on the back of the chip can be encapsulated through injection molding to form the encapsulating layer. After the plastic package encapsulating layer is completed, the upper surface of the encapsulating layer is polished to the required thickness in a mechanical grinding mode, meanwhile, photoresist or other high polymer materials on the surface of the chip are exposed, or when an injection mold is used for injection molding, the upper surface of a mold cavity directly contacts with the high polymer materials in the front functional area of the chip, so that injection molding resin cannot be injected to the surface of the high polymer materials. After the photoresist or other high polymer materials on the front sensing area of the chip are removed, the height of the front of the chip is lower than the surface of the encapsulating layer, and a groove structure is formed.

Drawings

Fig. 1 is a structure of a packaged structure according to the present invention, in which a photoresist or other polymer material on a front surface of a chip is removed by chemical solution or physical external force.

Fig. 2 to fig. 7 are schematic views of a packaging process of a package structure according to the present invention, wherein:

FIG. 2 is a schematic diagram of a high-precision electroforming frame used in a package structure according to the present invention, including a substrate, a metal pin module and a circuit;

FIG. 3 is a schematic structural diagram of a chip having a photoresist or other polymer material on the front surface thereof for protecting a front sensing region in a package structure according to the present invention, which is bonded to a substrate via a polymer bonding material;

FIG. 4 is a schematic structural diagram of a package structure according to the present invention, in which a bonding pad on the front side of a chip is connected to a metal pin module on a substrate by wire bonding;

FIG. 5 is a schematic diagram of an encapsulation layer structure encapsulating a chip, a pin and a lead by injection molding resin in a package structure according to the present invention;

FIG. 6 is a schematic structural diagram of a package structure according to the present invention, in which a substrate is physically separated from a polymer adhesive material and a metal pin module on the back of a chip by manual or mechanical operation;

FIG. 7 is a schematic diagram of a package structure according to the present invention in which the thickness of the encapsulation layer is reduced or thinned by mechanical grinding of the grinding process until the required thickness is achieved;

fig. 8 is a process flow annotation of an embodiment of the inventive package structure shown in fig. 1.

Fig. 9 is a schematic structural diagram of another packaging structure provided by the present invention after packaging, which is a structure obtained by removing the photoresist or other polymer material on the front side of the chip through chemical solution or physical external force.

Fig. 10 to fig. 15 are schematic views of another packaging structure provided by the present invention, wherein:

FIG. 10 is a schematic view of a high-precision electroforming frame used in another package structure of the present invention, including a substrate, a metal pin module, a metal pad and a circuit;

FIG. 11 is a schematic structural view of a chip having a front surface with a photoresist or other polymer material for protecting a front surface sensing region according to another embodiment of the present invention, bonded to a metal pad through a polymer bonding material;

FIG. 12 is a schematic view of another package structure according to the present invention, in which a bonding pad on the front surface of a chip is connected to a metal pin module on a substrate by wire bonding;

FIG. 13 is a schematic diagram of an encapsulation layer structure encapsulating a chip, a metal pin module, a metal pad and a lead by injection molding resin according to another package structure of the present invention;

FIG. 14 is a schematic structural view of another package structure according to the present invention, in which a substrate is physically separated from a polymer adhesive material and a metal pin module on the back of a chip by manual or mechanical operation;

fig. 15 is a schematic structural view of another package structure according to the present invention, in which the thickness of the encapsulation layer is reduced or thinned by mechanical grinding of the grinding process until the required thickness is achieved.

Fig. 16 is a process flow annotation of another embodiment of the inventive package structure shown in fig. 9.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.