阅读说明：本技术 电磁屏蔽结构的制备方法 (Preparation method of electromagnetic shielding structure ) 是由 陈建超 于上家 于 2021-08-13 设计创作，主要内容包括：本发明公开了一种电磁屏蔽结构的封装方法,包括以下制备方法：提供具有凹腔的下模,在所述下模的凹腔中覆盖一层导电膜；向覆盖有所述导电膜的所述凹腔中装入塑封材料；移动安装有基板的上模以靠近所述下模,合模得到粘接有所述导电膜的塑封层,所述基板上的芯片位于所述塑封层中；移动所述上模以远离所述下模,开模后从所述上模拆卸所述基板,得到所述电磁屏蔽结构。本发明将电磁屏蔽的工艺与压缩模塑的工艺同步进行,只需在装入塑封材料前在下模的凹腔中覆盖一层导电膜即可,无需后期采用磁控溅射设备在半导体结构的表面再单独制备电磁屏蔽膜,简化了工艺,提高了生产效率且降低了生产成本。(The invention discloses a packaging method of an electromagnetic shielding structure, which comprises the following preparation methods: providing a lower die with a cavity, and covering a layer of conductive film in the cavity of the lower die; filling a plastic packaging material into the cavity covered with the conductive film; moving an upper die provided with a substrate to be close to the lower die, and closing the die to obtain a plastic package layer adhered with the conductive film, wherein a chip on the substrate is positioned in the plastic package layer; and moving the upper die to be away from the lower die, and disassembling the substrate from the upper die after die opening to obtain the electromagnetic shielding structure. The electromagnetic shielding process and the compression molding process are synchronously carried out, only a layer of conductive film is covered in the concave cavity of the lower die before the plastic package material is filled, and the electromagnetic shielding film is not required to be independently prepared on the surface of the semiconductor structure by adopting magnetron sputtering equipment in the later period, so that the process is simplified, the production efficiency is improved, and the production cost is reduced.)

1. The packaging method of the electromagnetic shielding structure is characterized by comprising the following preparation steps of:

providing a lower die with a cavity, and covering a layer of conductive film in the cavity of the lower die;

filling a plastic packaging material into the cavity covered with the conductive film;

moving an upper die provided with a substrate to be close to the lower die, and closing the die to obtain a plastic package layer adhered with the conductive film, wherein a chip on the substrate is positioned in the plastic package layer;

and moving the upper die to be away from the lower die, and disassembling the substrate from the upper die after die opening to obtain the electromagnetic shielding structure.

2. The method for encapsulating an electromagnetic shielding structure according to claim 1, wherein the step of covering a cavity of the lower mold with a conductive film comprises:

and covering a release film in the cavity of the lower die, and covering a conductive film on the release film.

3. The method for encapsulating an electromagnetic shielding structure according to claim 2, wherein the release film is a double-sided release film.

4. A method for encapsulating an electromagnetic shielding structure according to claim 1, wherein the step of moving an upper mold having a substrate mounted thereon to be close to the lower mold and closing the mold to obtain the molding layer having the conductive film adhered thereto comprises:

and heating the lower die to melt the plastic packaging material, moving the upper die provided with the substrate in a direction close to the lower die to close the die, and obtaining a plastic packaging layer after the plastic packaging material is crosslinked and solidified.

5. The method for encapsulating an electromagnetic shielding structure according to claim 4, wherein the heating temperature is 100 to 200 ℃.

6. The method for encapsulating an electromagnetic shielding structure according to any of claims 1 to 5, wherein the conductive film contains a plurality of conductive particles.

7. The packaging method of the electromagnetic shielding structure according to any one of claims 1 to 5, wherein the molding compound mainly comprises epoxy resin and silicon dioxide or aluminum oxide.

8. A method for encapsulating an electromagnetic shielding structure according to any of claims 1 to 5, further comprising, before the step of moving an upper mold having a substrate mounted thereon to approach the lower mold and closing the mold to obtain a molding layer having the conductive film adhered thereto:

and providing a substrate, mounting a chip on the substrate, and fixing one surface of the substrate, which is deviated from the chip, on the upper die.

9. The method for encapsulating an electromagnetic shielding structure according to claim 8, wherein the step of mounting a chip on the substrate comprises:

and fixing the chip on the substrate, and welding and bonding the bonding area on the substrate and the chip by adopting a metal wire.

10. The method for encapsulating an electromagnetic shielding structure according to claim 9, wherein the step of fixing the chip on the substrate comprises:

dispensing glue on the substrate, bonding the chip at the dispensing position, and curing and baking.

Technical Field

The invention relates to the field of semiconductor packaging, in particular to a preparation method of an electromagnetic shielding structure.

Background

Electromagnetic waves play an increasingly important role in human society, but increasingly prominent electromagnetic radiation and electromagnetic interference in the semiconductor industry have a great negative impact on manufacturing and can seriously interfere with the stable operation of precision instruments and equipment. Generally, electromagnetic shielding measures are taken to reduce interference and radiation of electromagnetic waves to a protected object as much as possible, the electromagnetic shielding is a measure for preventing a high-frequency electromagnetic field from being transmitted in space by using a shielding body, and the shielding body can avoid the problem of system performance deterioration caused by electromagnetic noise or interference generated in the same system or different systems. At present, the electromagnetic shielding mode generally adopts the mode that a semiconductor structure after plastic package is subjected to half cutting, and then an electromagnetic shielding film is covered on the surface of a product through magnetron sputtering, so that the electromagnetic shielding effect is achieved, special magnetron sputtering equipment is needed, the process is complex, and the production cost is high.

Disclosure of Invention

The invention mainly aims to provide a preparation method of an electromagnetic shielding structure, aiming at solving the problems of complex process and high cost of the existing electromagnetic shielding.

In order to achieve the above object, the present invention provides a packaging method of an electromagnetic shielding structure, comprising the following preparation steps:

providing a lower die with a cavity, and covering a layer of conductive film in the cavity of the lower die;

filling a plastic packaging material into the cavity covered with the conductive film;

moving an upper die provided with a substrate to be close to the lower die, and closing the die to obtain a plastic package layer adhered with the conductive film, wherein a chip on the substrate is positioned in the plastic package layer;

and moving the upper die to be away from the lower die, and disassembling the substrate from the upper die after die opening to obtain the electromagnetic shielding structure.

Optionally, the step of covering a conductive film in the cavity of the lower mold includes:

and covering a release film in the cavity of the lower die, and covering a conductive film on the release film.

Optionally, the release film is a double-sided release film.

Optionally, the moving the upper mold with the substrate mounted thereon to approach the lower mold, and the step of closing the mold to obtain the molding layer with the conductive film bonded thereto includes:

and heating the lower die to melt the plastic packaging material, moving the upper die provided with the substrate in a direction close to the lower die to close the die, and obtaining a plastic packaging layer after the plastic packaging material is crosslinked and solidified.

Optionally, the heating temperature is 100-200 ℃.

Optionally, the conductive film comprises a plurality of conductive particles therein.

Optionally, the plastic package material mainly includes epoxy resin and silicon dioxide or aluminum oxide.

Optionally, before the step of moving the upper mold with the substrate mounted thereon to approach the lower mold and closing the mold to obtain the molding layer with the conductive film adhered thereon, the method further includes:

and providing a substrate, mounting a chip on the substrate, and fixing one surface of the substrate, which is deviated from the chip, on the upper die.

Optionally, the step of mounting a chip on the substrate includes:

and fixing the chip on the substrate, and welding and bonding the bonding area on the substrate and the chip by adopting a metal wire.

Optionally, the step of fixing the chip on the substrate includes:

dispensing glue on the substrate, bonding the chip at the dispensing position, and curing and baking.

According to the technical scheme, firstly, a layer of conductive film is covered in a cavity of a lower die, then compression molding is carried out, plastic package materials are filled in the cavity, an upper die provided with a substrate is moved to be close to the lower die, a plastic package layer adhered with the conductive film is obtained after die assembly, a chip of the substrate is covered by the plastic package layer, finally the upper die is moved to be far away from the lower die, and the substrate is detached from the upper die after die opening, so that the electromagnetic shielding structure covered with the conductive film can be obtained. The electromagnetic shielding process and the compression molding process are synchronously carried out, only a layer of conductive film is covered in the concave cavity of the lower die before the plastic package material is filled, and the electromagnetic shielding film is not required to be independently prepared on the surface of the semiconductor structure by adopting magnetron sputtering equipment in the later period, so that the process is simplified, the production efficiency is improved, and the production cost is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic flow chart of a first embodiment of a method for manufacturing an electromagnetic shielding structure according to the present invention;

fig. 2 is a schematic flow chart of a method for manufacturing an electromagnetic shielding structure according to a second embodiment of the present invention;

fig. 3 is a schematic flow chart of a method for manufacturing an electromagnetic shielding structure according to a third embodiment of the present invention;

FIG. 4 is a schematic view of a cavity of a lower mold covered with a release film according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a cavity of a lower mold covered with a release film and a conductive film according to an embodiment of the present invention;

FIG. 6 is a schematic view of a cavity of a lower mold being filled with a molding material according to an embodiment of the present invention;

FIG. 7 is a schematic view of the closing of the upper and lower dies according to one embodiment of the invention;

fig. 8 is a schematic diagram of an electromagnetic shielding structure obtained after the mold is opened according to an embodiment of the invention.

The reference numbers illustrate:

10	upper die	20	Lower die
				11	Concave cavity	30	Electromagnetic shielding structure
31	Substrate	32	Plastic packaging layer
				33	Chip and method for manufacturing the same	34	Conductive film
35	Plastic packaging material	40	Release film

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The invention provides a packaging method of an electromagnetic shielding structure, and fig. 1 is a schematic flow chart of a first embodiment of the packaging method of the electromagnetic shielding structure 30, which comprises the following preparation steps:

s10, as shown in fig. 5, providing a lower mold 20 having a cavity 21, and covering a conductive film 34 in the cavity 21 of the lower mold 20;

as shown in fig. 7, the mold includes an upper mold 10 and a lower mold 20 which are disposed opposite to each other, the lower mold 20 has a cavity 21, a substrate 31 is fixed to the upper mold 10, compression molding is performed using the mold and a press, and a conductive film 34 is covered in the cavity 21 of the lower mold 20 before compression molding. The conductive film 34 extends along the bottom wall and the side wall of the cavity 21 of the lower mold 20, and both ends of the conductive film 34 can extend out of the cavity 21 to ensure the sealing performance during mold closing and prevent the plastic sealing material 35 from leaking. Compression molding is generally referred to as compression molding, and is a method in which a preform in the form of powder, granules, pellets, or sheets, or even a preform shaped like a product, is placed in a cavity of a heated mold, and then the mold is closed and pressed to form and cure or vulcanize the preform, and then the preform is removed from the mold to obtain a product, which is particularly suitable for the molding of thermosetting plastics.

S20, as shown in fig. 6, filling the cavity 21 covered with the conductive film 34 with a molding compound 35;

the molding compound 35 may be in a powder form, and then cured by heating, and the amount of the molding compound 35 filled into the cavity 21 may be selected according to specific needs as long as it is ensured that the chip 33 or the electronic component on the substrate 31 is wrapped by the molding compound 35.

S30, as shown in fig. 7, moving the upper mold 10 with the substrate 31 mounted thereon to approach the lower mold 20, and closing the molds to obtain the molding layer 32 with the conductive film 34 adhered thereon, wherein the chip 33 on the substrate 31 is located in the molding layer 32;

the upper die 10 of the die can move relative to the lower die 20, the upper die 10 is controlled to be close to the lower die 20, the die is pressed and closed, a plastic package layer 32 is obtained through cross-linking and curing of a plastic package material 35, the conductive film 34 is fixed with the plastic package layer 32, the chip 33 of the substrate 31 is wrapped by the plastic package layer 32, and the plastic package layer 32 is used for protecting the chip 33 or a component so as to prevent the electrical performance from being reduced due to corrosion of impurities in the air to a circuit.

S40, moving the upper mold 10 away from the lower mold 20, and detaching the substrate 31 from the upper mold 10 after opening the mold, thereby obtaining the electromagnetic shielding structure 30 shown in fig. 8.

The upper mold 10 is controlled to move away from the lower mold 20, after the mold is opened, the conductive film 34 follows the substrate 31 and leaves the cavity 21 of the lower mold 20, then the substrate 31 is removed from the upper mold 10, the portion of the conductive film 34 extending out of the substrate 31 can be cut, and the conductive film 34 is covered on the surface of the plastic-sealed layer 32 as an electromagnetic shielding layer, so as to obtain the electromagnetic shielding structure 30 of the present embodiment.

In the embodiment, the electromagnetic shielding and the compression molding are completed at one time by combining the electromagnetic shielding with the compression molding, only a conductive film 34 is covered in advance in the cavity 21 of the lower mold 20, and a magnetron sputtering device is not needed to sputter the surface of the plastic package layer 32 to form the electromagnetic shielding layer, so that the production efficiency can be effectively improved on the basis of reducing the equipment cost.

Further, referring to fig. 2, which is a flowchart illustrating a second embodiment of the method for encapsulating the electromagnetic shielding structure 30 according to the present invention, based on the first embodiment, the step S10 includes:

s11, as shown in fig. 4, a release film 40 is covered in the cavity 21 of the lower mold 20, and a conductive film 34 is covered on the release film 40.

The release film 40 is a film whose surface can be distinguished, the release film 40 does not have viscosity after contacting the conductive film 34, a layer of release film 40 is covered in the cavity 21 of the lower mold 20, when the upper mold 10 is controlled to leave the lower mold 20, the conductive film 34, the plastic-sealed layer 32 and the substrate 31 leave the lower mold 20 along with the upper mold 10, and the release film 40 is still located in the cavity 21 of the lower mold 20, that is, the conductive film 34 and the release film 40 can be separated, so that the electromagnetic shielding structure 30 can be separated from the lower film smoothly. From the diapire and the lateral wall that mould film 40 was likewise followed lower mould 20 cavity 21 and is spreaded, and from the outside of the both ends protractile recess of mould film 40, can guarantee the leakproofness after last mould 10 and the lower mould 20 compound die, prevent to flow outward to the outside of mould cavity after the melting of plastic packaging material 35, be convenient for moreover the later stage peel off mould film 40 from lower mould 20.

The release film 40 is preferably a double-sided release film 40, that is, both sides of the release film 40 do not have viscosity with the conductive film 34 and the lower mold 20, and after the mold is opened, the release film 40 does not leave the cavity 21 of the lower mold 20 along with the conductive film 34, and the release film 40 is conveniently peeled from the cavity 21 of the lower mold 20, so that the production efficiency is further improved. In other embodiments, the release film 40 may be omitted, and the conductive film may be directly spread on the lower mold 20 and then encapsulated with the encapsulating material 35.

Further, based on the first embodiment, referring to fig. 3, step S30 of the third embodiment of the packaging method for the electromagnetic shielding structure 30 of the present invention includes:

and S31, heating the lower die 20 to melt the plastic package material 35, moving the upper die 10 provided with the substrate 31 in the direction close to the lower die 20 to clamp the dies, and obtaining the plastic package layer 32 after the plastic package material 35 is crosslinked and solidified.

The plastic package material 35 can be powdered thermosetting plastic, the lower die 20 is provided with a heater, the plastic package material 35 is heated by the heater of the lower die 20, then the die is closed and pressurized, and the die cavity is filled with the plastic package material 35 under the action of pressure; and heating, so that the molten plastic package material 35 is subjected to a cross-linking reaction and is cross-linked and solidified with the conductive film 34, and the conductive film 34 can cover the plastic package layer 32. In the embodiment, the plastic package material 35 is heated and cross-linked and cured to form the plastic package layer 32, the process is simple, the conductive film 34 and the plastic package layer 32 are fixed, the electromagnetic shielding and compression molding processes are performed synchronously, the process is simplified, and the production efficiency is improved. It is understood that in other embodiments, the upper mold and the lower mold 20 may be clamped together, heated to melt the molding compound 35, and then heated to crosslink the molding compound to obtain the molding layer 32.

The plastic package material 35 mainly includes epoxy resin and silica or alumina, the plastic package material 35 of this embodiment uses epoxy resin as a base, and silica or alumina is added as an inorganic filler, and the silica as a filler can reduce shrinkage, enhance toughness, enhance wear resistance, reduce water absorption, improve thermal deformation temperature, improve thermal conductivity, reduce thermal expansion coefficient, reduce cost, and the like of the plastic package material 35. In this example, it is preferable to use a spherical fine silica powder, which has a larger loading amount, good fluidity, crack resistance, and the like than a horn-shaped fine silica powder. The temperature for heating the plastic package material 35 is 100-200 ℃ to ensure that the plastic package material 35 can be fully melted. In some other embodiments, the molding compound may include a resin, which may be an epoxy resin and/or a phenolic resin, a metal hydroxide, carbon black, and silica and/or alumina. The metal hydroxide can be used for flame retardance, and the carbon black is used for coloring, so that subsequent mark marking identification is facilitated.

The conductive film 34 contains a plurality of conductive particles, the conductive particles in the conductive film 34 are pressed together when the mold is closed, and the conductive particles are contacted together, so that the conductive layer can be formed through contact conduction and serves as an electromagnetic shielding layer of a semiconductor structure. And the molding compound 35 is heated to generate cross-linking and curing with the conductive film 34, so that the conductive film 34 is fixed on the molding layer 32. The plastic packaging layer 32 and the electromagnetic shielding layer are obtained by compression molding at the same time, so that the process is simplified, and the production efficiency is improved.

Based on the first embodiment, step S30 of the fourth embodiment of the method for packaging the electromagnetic shielding structure 30 of the present invention further includes: providing a substrate 31, mounting a chip 33 on the substrate 31, and fixing one surface of the substrate 31, which is far away from the chip 33, on the upper die 10.

After the surface mounting of the substrate 31 is completed, the substrate 31 may be fixed to the upper film, the chip 33 and the electronic component on the substrate 31 face the lower die 20, the upper die 10 is controlled to move toward the lower die 20 so as to embed the chip 33 and the electronic component on the substrate 31 in the molding compound 35, and after the molding compound 35 is cured, the chip 33 and the electronic component are wrapped by the molding compound 32, and the molding compound 32 and the substrate 31 are respectively bonded and fixed to the substrate 31 and the conductive film 34.

Further, the step of mounting the chip 33 on the substrate 31 includes: fixing the chip 33 on the substrate 31, and bonding the bonding region on the substrate 31 and the chip 33 by wire bonding. Specifically, a plurality of chip assemblies can be mounted on a preset area of the substrate 31 in a one-to-one correspondence manner, and a bonding area on the substrate 31 and each chip monomer of the functional module are bonded by welding with a welding material.

The "wire bonding" is to bond gold wires, and the bare chip 33 and the bonding region on the substrate 31 are bonded together by gold wires using a high-precision bonding apparatus. Firstly, cleaning the substrate 31 by using a plasma cleaning machine to remove surface pollutants, exposing more surface areas, roughening the surface of the substrate 31, enhancing the bonding force between a gold wire and a gold finger of the substrate 31, and then welding by using a high-speed full-automatic lead welding machine with the welding precision of +/-2 microns. The plasma is a state of a substance, which is also called a fourth state of a substance, and is not a common solid-liquid-gas three-state, and it is a plasma state by applying sufficient energy to a gas to ionize the gas. The "active" components of the plasma include: ions, electrons, atoms, active groups, excited nuclides, photons and the like, and the plasma cleaning machine is used for treating the surface of a sample by utilizing the properties of the active components so as to achieve the purposes of cleaning, coating and the like.

More specifically, the step of fixing the chip 33 on the substrate 31 includes: dispensing on the substrate 31, adhering the chip 33 to the dispensing position, and curing and baking.

Firstly, whether a substrate is dirty or not and whether warping degree exceeds the standard or not are inspected, then solder paste is printed, electronic components such as capacitors are bonded on the substrate by a chip mounter, the electronic components are reflow-welded on the substrate by a reflow furnace, and the substrate is cleaned and subjected to AOI (automatic Optical Inspection) Inspection. The AOI is equipment for detecting common defects encountered in welding production based on an optical principle, and various different mounting errors and welding defects on a PCB are automatically detected by using a high-speed high-precision vision processing technology. The die 33 may then be bonded to the substrate 31 using a die bonder, which may include dispensing, bonding, curing, and baking.

The above is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by the present specification or directly/indirectly applied to other related technical fields under the spirit of the present invention are included in the scope of the present invention.