CN105023883A - Plastic package and preparation method thereof - Google Patents

Abstract

The present invention relates to a plastic package and a preparation method thereof. The plastic package includes a chip 1, a support 2 for supporting the chip 1 and a packaging case 5, wherein the package case 5 includes covering the chip 1 so that the chip 1 a sealed first plastic sealing layer 3 and a second plastic sealing layer 4 covering the first plastic sealing layer 3 to seal the first plastic sealing layer 3, wherein the first plastic sealing layer 3 is made of a first resin material; The second plastic sealing layer 4 is made of a second resin material; and the equivalent thermal expansion coefficient of the first resin material is smaller than the equivalent thermal expansion coefficient of the second resin material. The plastic package provided by the invention has a wide selection of materials, and can reduce product delamination failure, thereby improving product reliability.

Description

A kind of plastic packaging and preparation method thereof

technical field

The invention relates to a plastic package and a preparation method thereof.

Background technique

With the rapid development of electronic science and technology, the process of semiconductor industrialization is also constantly developing. In recent years, electronic packaging is developing in the direction of high density, light weight, narrow pitch, low distribution, multi-function, and suitable for surface mounting. Divided from the materials used in packaging, electronic packaging can be mainly divided into metal packaging, ceramic packaging and plastic packaging. The former two are hermetic packages with high reliability, but due to high cost, these two packages are mostly used in aerospace and other fields with high performance requirements for devices. Plastic packaging is a non-hermetic packaging. This packaging form is less reliable than the previous two forms, but because of its low cost and simple process, it is widely used in people's lives. At present, plastic packaging has become the mainstream in the market and is widely used in the field of civilian consumer electronics products.

Traditional materials used for plastic packaging need to have the following characteristics: good insulation, temperature adaptability, radiation resistance, thermal expansion coefficient (CTE) close to the material of the contact chip and support, good chemical stability , Good adhesion with support materials, good compactness and low cost, etc. Based on the above characteristics, the traditional plastic packaging material is mainly thermosetting epoxy resin. The advantages of epoxy resin are excellent electrical properties, good mechanical strength, small shrinkage after molding, good chemical corrosion resistance, certain radiation and moisture resistance, and high temperature resistance. However, its disadvantages are that it has poor adhesion to the chip in contact with the package and the support, and it is difficult to match the coefficient of thermal expansion between the chip in contact with the package and the support for supporting the chip.

The so-called failure refers to the loss of the original design function of the product. In industrial production, there are various forms of product failure, but delamination failure is a common failure form. The delamination failure is mainly due to the mismatch between the thermal expansion coefficient of the molding compound and the thermal expansion coefficient between the substrate or the lead frame, and the delamination occurs at high temperature, resulting in failure. In addition, due to the insufficient moisture resistance of the molding compound, the entry of water vapor will also lead to delamination failure or popcorn phenomenon. Furthermore, delamination failures can also occur due to poor adhesion of the epoxy to the die and substrate or lead frame it contacts during packaging. Delamination failure seriously affects the reliability of electronic packaging, causing huge losses to enterprises.

Therefore, how to reduce the delamination failure of the product so as to improve the reliability of the plastic packaging of the product remains to be further studied.

Contents of the invention

The purpose of the present invention is to overcome the problem that the plastic package in the prior art is prone to delamination failure, thereby reducing the reliability of the product, and to provide a plastic package that can reduce the delamination failure of the product and improve the reliability of the product.

The present invention provides a plastic package, which includes a chip, a support 2 for supporting the chip 1, and a package case 5, wherein the package case 5 includes a first package that covers the chip 1 to make the chip 1 hermetically sealed. The plastic sealing layer 3 and the second plastic sealing layer 4 covering the first plastic sealing layer 3 to seal the first plastic sealing layer 3, wherein the first plastic sealing layer 3 is made of a first resin material; the second plastic sealing layer 4 Made of a second resin material; and the equivalent thermal expansion coefficient of the first resin material is smaller than the equivalent thermal expansion coefficient of the second resin material.

The present invention also provides a method for preparing a plastic package, the method comprising the following steps:

a. Mount the chip 1 on the support 2;

b. coating the first plastic sealing layer 3 on the chip 1 to realize the sealing of the chip 1;

c. Wrapping the second plastic sealing layer 4 on the first plastic sealing layer 3 to realize the sealing of the first plastic sealing layer 3 .

In the present invention, the inventor of the present invention finds through a large amount of scientific researches: the traditional chip structure is that chip, silver paste (or patch adhesive) and substrate (or nail frame) directly contact with molding compound, like this chip, silver paste (or patch glue) and the substrate (or nail frame) and the molding compound will appear due to insufficient adhesion, thermal expansion coefficient mismatch and water vapor inhalation leading to delamination. The inventor of the present invention uses the first plastic sealing layer and the second plastic sealing layer prepared by two materials to replace the molding compound of only one material for packaging, and the first plastic sealing layer is directly in contact with the chip, the substrate, etc., the second The second plastic sealing layer is outside the first plastic sealing layer, directly in contact with the air, and the equivalent thermal expansion coefficient of the first resin material for preparing the first plastic sealing layer 3 is smaller than that of the second resin material for preparing the second plastic sealing layer 4 Equivalent coefficient of thermal expansion. Compared with the traditional plastic package, the plastic package of the present invention and the plastic package prepared by the method of the present invention can make the combination of chips, substrates, etc. and the first plastic package better due to the introduction of the first plastic package, and improve the The mismatch of thermal expansion coefficient can greatly reduce the stress and improve the overall reliability; in addition, due to the introduction of the second plastic sealing layer, the mechanical properties, corrosion resistance, and moisture resistance of the chip are improved, making the package There will be no popcorn phenomenon inside due to the thermal expansion of water vapor, which also improves the overall reliability; in addition, because two kinds of materials are introduced to replace the original molding compound material for the molding process, the original needs will be concentrated in the The elements of one material are distributed to two materials, which greatly improves the choice of materials.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, together with the following specific embodiments, are used to explain the present invention, but do not constitute a limitation to the present invention. In the attached picture:

1 is a cross-sectional view of a plastic package in the form of a thin, small-size package in the prior art;

2 is a cross-sectional view of a plastic package in the form of a thin, small-size package provided by the present invention;

3 is a cross-sectional view of a plastic package in the form of a ball grid array package in the prior art;

FIG. 4 is a cross-sectional view of a plastic package in the form of a ball grid array package provided by the present invention.

Explanation of reference signs

1. Chip 2. Support

3. The first plastic sealing layer 4. The second plastic sealing layer

5. Encapsulation shell

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

The terms and words used in this specification and claims should not be construed as being limited to typical meanings or dictionary definitions, but should be understood as having meanings and concepts related to the technical field of the present invention, according to which the invention The author is able to appropriately define the terms and concepts that best describe the best method known to him or her to practice the invention.

In the present invention, the term "support" refers to the object used to support the chip during the packaging process. In the case of thin small outline package (SOP), the "support" refers to the lead frame; in the case of ball grid array In the case of a structural package (BGA), the "support" refers to the substrate.

Generally, the term "thermal expansion coefficient" refers to the phenomenon of expansion and contraction of an object due to temperature changes. When it is heated and expanded, its ability to change is represented by the expansion rate per unit temperature change. In the present invention, the term "thermal expansion coefficient" is used to represent expansion and contraction phenomena of materials other than resin materials. The term "equivalent thermal expansion coefficient" is due to the fact that the thermal expansion coefficient of the resin material is composed of two parts. When the temperature is lower than the glass transition temperature, the thermal expansion coefficient is small, generally about 10ppm; when the temperature is greater than the glass transition temperature, the thermal expansion coefficient It is very large, generally dozens of ppm, so the two-stage thermal expansion coefficient is equivalent to the value averaged by temperature, that is, the equivalent thermal expansion coefficient. In the present invention, the term "equivalent thermal expansion coefficient" is used to represent the phenomenon of expansion and contraction of the resin material.

The present invention provides a plastic package, which includes a chip 1, a support 2 for supporting the chip 1, and a package case 5, wherein the package case 5 includes a package that covers the chip 1 to make the chip 1 hermetically sealed. The first plastic sealing layer 3 and the second plastic sealing layer 4 covering the first plastic sealing layer 3 so that the first plastic sealing layer 3 is sealed, wherein, the first plastic sealing layer 3 is made of a first resin material; the second plastic sealing layer Layer 4 is made of a second resin material; and the equivalent thermal expansion coefficient of the first resin material is smaller than the equivalent thermal expansion coefficient of the second resin material.

According to the present invention, the material of the support member 2 is not specifically limited, it can be a material well known to those skilled in the art; and the shape of the support member 2 is not specifically limited, as long as the chip 1 can be It only needs to be supported, and it can be an integral structure (ie, a substrate) or a non-integral structure (ie, a lead frame).

According to the present invention, the first resin material and the second resin material are not specifically limited, they can be resin materials well known to those skilled in the art, preferably, for the first resin material for preparing the first plastic sealing layer 3 The requirement is mainly that the bond strength is good. The equivalent thermal expansion coefficient of the first resin material and the thermal expansion coefficient of the material in direct contact can be well matched, and there is no need for particularly good mechanical strength, strong chemical corrosion resistance, and good resistance to corrosion. In this way, on the one hand, due to the good bonding strength between the first plastic sealing layer 3 and materials such as chips and substrates, shear or pull failure is not easy to occur, and on the other hand, because the first plastic sealing layer 3 is prepared The equivalent thermal expansion coefficient of the resin material matches well with the thermal expansion coefficient of the chip, substrate and other materials, which can reduce the stress caused by the expansion between different materials during the heating process, so that there will be no serious during the baking process. delamination phenomenon. Preferably, the requirements for the second resin material for preparing the second plastic seal layer 4 are mainly good mechanical strength, good chemical corrosion resistance, good radiation resistance and moisture resistance, etc., and, due to the preparation of the first plastic seal layer 3 Both the first resin material and the second resin material for preparing the second plastic encapsulation layer 4 are organic materials, so the selection of the equivalent thermal expansion coefficient and bonding strength of the second resin material is very wide.

Preferably, both the first resin material and the second resin material are thermosetting resin materials;

More preferably, the first resin material and the second resin material are each a thermosetting epoxy resin.

According to the present invention, the thermosetting epoxy resin is not specifically limited, and it can be a thermosetting epoxy resin known to those skilled in the art that can be used for plastic packaging.

According to the present invention, the thickness of the first plastic sealing layer 3 is not specifically limited, it can be determined according to the experience of those skilled in the art, as long as the chip 1 can be covered to seal the chip 1; the same reason , the thickness of the second plastic sealing layer 4 is not specifically limited, it can be determined according to the experience of those skilled in the art, as long as the first plastic sealing layer 3 can be covered so that the first plastic sealing layer 3 can be sealed .

According to the present invention, various packaging forms used for integrated circuit packaging can be used for the plastic package without limitation. Preferably, the packaging form of the plastic package is a dual in-line package, a thin small size package, a flat One or more of type package and ball grid array structure package.

According to the present invention, the difference between the equivalent thermal expansion coefficient of the second resin material and the equivalent thermal expansion coefficient of the first resin material may be 3×10 ^-6 /°C-15×10 ^-6 /°C, preferably , the difference between the equivalent thermal expansion coefficient of the second resin material and the equivalent thermal expansion coefficient of the first resin material is 5×10 ^-6 /°C-12×10 ^-6 /°C, more preferably, the The difference between the equivalent thermal expansion coefficient of the second resin material and the equivalent thermal expansion coefficient of the first resin material is 8×10 ^-6 /°C-10×10 ^-6 /°C.

According to the present invention, the equivalent thermal expansion coefficient of the second resin material is 10×10 ^-6 /°C-30×10 ^-6 /°C, preferably 12×10 ^-6 /°C-20×10 ^-6 /°C, More preferably, it is 15×10 ^-6 /°C to 18×10 ^-6 /°C.

The present invention also provides a method for preparing a plastic package, the method comprising the following steps:

a. Mount the chip 1 on the support 2;

b. coating the first plastic sealing layer 3 on the chip 1 to realize the sealing of the chip 1;

c. Wrapping the second plastic sealing layer 4 on the first plastic sealing layer 3 to realize the sealing of the first plastic sealing layer 3 .

According to the present invention, the material of the support member 2, the first resin material for preparing the first plastic sealing layer 3 and the second resin material for preparing the second plastic sealing layer 4; the first resin material and the first resin material The equivalent thermal expansion coefficients of the two resin materials; the thicknesses of the first plastic sealing layer 3 and the second plastic sealing layer 4;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, the present invention will be described in detail by taking the package form of thin small size package (SOP) and the package form of ball grid array structure as examples.

As shown in Figure 1, Figure 1 is a cross-sectional view of a plastic package in the form of a thin and small-sized package in the prior art. The thermal expansion coefficient also needs to consider the bonding performance of the plastic package and the substrate and the chip, and also needs to consider the mechanical strength, corrosion resistance and moisture resistance of the plastic package, etc. Therefore, the plastic package made of The choice of materials was very demanding.

As shown in Figure 2, Figure 2 is a cross-sectional view of a plastic package in the form of a thin and small-sized package provided by the present invention, as can be seen from Figure 2, the plastic package includes a chip 1, a support member 2 for supporting the chip 1, and a package shell body 5, wherein the packaging case 5 includes a first plastic encapsulation layer 3 covering the chip 1 to seal the chip 1 and a second plastic encapsulation layer 4 covering the first plastic encapsulation layer 3 to seal the first plastic encapsulation layer 3, Wherein, the first plastic sealing layer 3 is made of a first resin material; the second plastic sealing layer 4 is made of a second resin material; and the equivalent thermal expansion coefficient of the first resin material is smaller than that of the second resin The equivalent thermal expansion coefficient of the material. Since the equivalent thermal expansion coefficient of the first resin material is relatively low, it is located between the chip and the support member material, and is as close as possible to the thermal expansion coefficient of the chip, thus avoiding the occurrence of stress due to an excessive difference in thermal expansion coefficient during the baking process; The second plastic sealing layer 4 is wrapped on the outside of the first plastic sealing layer 3, which mainly plays the role of protection. The second plastic sealing layer 4 is not directly in contact with the chip 1 and the support member 2 (lead frame), so the The selection space for the equivalent thermal expansion coefficient of the second resin material is relatively large, as long as it is higher than the equivalent thermal expansion coefficient of the first resin material, it can be as close as possible to the thermal expansion coefficient of the support to reduce the stress caused by thermal mismatch .

In this way, on the one hand, better matching and better bonding of the coefficient of thermal expansion between the first resin material and the chip and the support can be achieved, and on the other hand, it can ensure that the second resin material has good mechanical properties, Corrosion resistance and water vapor resistance, which can reduce delamination failure and improve product reliability.

As shown in FIG. 3 , FIG. 3 is a cross-sectional view of a plastic package in the form of a ball grid array package in the prior art. It can be seen from FIG. 3 that the structure of the plastic package is the same as that of the plastic package shown in FIG. 1 , The difference is that the support 2 in FIG. 3 is an integral structure (that is, in the case of a ball grid array package (BGA), the support 2 is a substrate), while the support 2 shown in FIG. 1 is a non- One-piece structure (ie, in the case of a thin small outline package (SOP), the support 2 is a lead frame).

As shown in Figure 4, Figure 4 is a cross-sectional view of a plastic package in the form of a ball grid array package provided by the present invention. It can be seen from Figure 4 that the structure of the plastic package is the same as that of the plastic package shown in Figure 2, so The difference is that the support 2 in FIG. 4 is an integral structure (that is, in the case of a ball grid array package (BGA), the support 2 is a substrate), while the support 2 shown in FIG. 2 is non-integral structure (ie, in the case of a thin small outline package (SOP), the support 2 is a lead frame).

Therefore, in the present invention, the biggest difference between the plastic package in the form of thin small size package and the plastic package in the form of ball grid array structure lies in whether the support member 2 adopts a lead frame or a substrate. In addition, descriptions that overlap with the content of the plastic package in the form of a thin small size package and the plastic package in the form of a ball grid array structure of the present invention will be omitted.

The specific embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details in the above-mentioned embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not further described in the present invention.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (8)

1. a Plastic Package, this Plastic Package comprises chip (1), in order to the strutting piece (2) of supporting chip (1) and encapsulating housing (5), it is characterized in that, described encapsulating housing (5) comprises coating chip (1) with the first plastic packaging layer (3) making chip (1) seal and coated first plastic packaging layer (3) with the second plastic packaging layer (4) making the first plastic packaging layer (3) seal, wherein, described first plastic packaging layer (3) is made up of the first resin material; Described second plastic packaging layer (4) is made up of the second resin material, and the fiber yarn of described first resin material is less than the fiber yarn of described second resin material.

2. Plastic Package according to claim 1, wherein, described first resin material and described second resin material are thermoset resin material.

3. Plastic Package according to claim 2, wherein, described first resin material and described second resin material are thermosetting epoxy resin separately.

4. Plastic Package according to claim 1, wherein, the packing forms of described Plastic Package is one or more in the encapsulation of dip, Outline Package, Flat type packaged and ball grid array structure.

5. according to the Plastic Package in claim 1-4 described in any one, wherein, the difference of the fiber yarn of described second resin material and the fiber yarn of described first resin material is 3 × 10 ^-6/ DEG C-15 × 10 ^-6/ DEG C.

6. Plastic Package according to claim 5, wherein, the difference of the fiber yarn of described second resin material and the fiber yarn of described first resin material is 5 × 10 ^-6/ DEG C-12 × 10 ^-6/ DEG C.

7. the Plastic Package according to claim 1 or 6, wherein, the fiber yarn of described second resin material is 10 × 10 ^-6/ DEG C-30 × 10 ^-6/ DEG C, be preferably 12 × 10 ^-w/ DEG C-20 × 10 ^-6/ DEG C.

8. the preparation method of the Plastic Package in claim 1-7 described in any one, the method comprises the following steps:

A, by chip (1) attachment on strutting piece (2);

B, the first plastic packaging layer (3) to be coated on described chip (1) to realize the sealing of described chip (1);

C, the second plastic packaging layer (4) to be coated on described first plastic packaging layer (3) to realize the sealing of described first plastic packaging layer (3).