CN103624909B - For reducing fixture and the method thereof of plastic-sealed body bending - Google Patents

Abstract

The invention provides a clamp for reducing the bending of a plastic package and a method thereof, which belong to the technical field of integrated circuit chip packaging. The fixture includes an upper pressing plate and a lower pressing plate, and the molded body in the plastic-encapsulated cooling process is placed between the upper pressing plate and the lower pressing plate and clamped by the upper pressing plate and the lower pressing plate to reduce the bending of the plastic packaging body. The fixture has an obvious effect of improving the bending of the plastic package, and the method is simple and efficient.

Description

Fixture and method for reducing bending of plastic package

technical field

The invention belongs to the technical field of integrated circuit chip packaging, and relates to the plastic sealing process of packaging, in particular to the use of clamps to clamp and press the plastic packaged body after the plastic package has been released from the mold to prevent the plastic packaged body from bending during the cooling process.

Background technique

The encapsulated integrated circuit chip is basically wrapped by the plastic encapsulant from the outside, and the outer pins of the conductor part of the lead frame protrude from the plastic encapsulant. The wrapped plastic compound is usually called "plastic package", which has the function of protecting the internal chip and the soft metal wire, and then, the packaged integrated circuit chip can be used conveniently.

Therefore, the packaging process of integrated circuit chips includes the process of forming a plastic package, which is usually called a plastic packaging process. The plastic encapsulation process is also a thermal process (that is, undergoes significant temperature changes). Therefore, after the plastic encapsulation is formed, the thermal stress will usually cause the plastic encapsulation to bend in the plastic encapsulation, thereby causing the packaged integrated circuit chip to deform. The deformation caused by this bending may cause serious problems during use, and reducing the bending of the plastic package is also a problem that has been devoted to solving in this field.

In today's semiconductor packaging industry, there are usually two solutions to reduce the bending of the plastic package:

The first is to reduce the bending of the plastic package from the source through precise design in the process of designing integrated circuit chip products; for example, the Chinese patent application number is CN1122637, and the name is "planar plastic packaging module for integrated circuits" In the Chinese patent, it provides an additional layer of material in the plastic at a layer different from that of the lead frame to connect the leads, so as to balance the various forces, thereby reducing the bending of the molded body;

The second is the method of adjusting parameters or changing the shape and material of the molding resin structure during the molding process.

Among them, the first solution requires high design technology, and it is difficult to completely avoid the bending phenomenon. Once the design is not perfect, the bending of the plastic package will exceed the standard requirements; the second solution can alleviate the bending problem by improving the process conditions and materials, but, It is also difficult to meet the standard requirements for integrated circuit chip products with larger plastic packages.

Contents of the invention

The purpose of the present invention is to reduce the bending degree of the plastic package.

To achieve the above objects or other objects, the present invention provides the following technical solutions.

According to one aspect of the present invention, there is provided a fixture for reducing the bending of a plastic package, which includes an upper press plate and a lower press plate, and the plastic package in the cooling process of plastic packaging is placed between the upper press plate and the lower press plate And be clamped and pressed by the upper pressing plate and the lower pressing plate.

In the jig according to an embodiment of the present invention, a cavity for positioning the plastic package is provided on the upper surface of the lower pressing plate.

The jig according to still another embodiment of the present invention, wherein the jig further includes a carrier for carrying and transferring the plastic package, and the plastic package and the carrier are simultaneously placed between the upper pressing plate and the lower pressing plate.

In the fixture of any of the above-mentioned embodiments, preferably, a groove is provided on the upper surface of the lower pressing plate, and the plastic package carrier placed between the upper pressing plate and the lower pressing plate is placed in the groove middle.

In the clamp in any of the foregoing embodiments, preferably, the carrying plate includes a carrying frame and a handle, and the carrying frame is embedded in the groove.

According to still another embodiment of the jig of the present invention, wherein the upper pressing plate or the lower pressing plate is provided with a cooling component for accelerating the cooling of the plastic package.

According to another embodiment of the fixture of the present invention, wherein, the surface roughness of the upper pressing plate acting on the plastic package is greater than or equal to Ra1 and less than or equal to Ra2, and the roughness of the upper pressing plate acting on the plastic package is The flatness of the surface is greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

In the fixture of any of the aforementioned embodiments, preferably, the roughness of the bottom surface of the cavity is greater than or equal to Ra0.1 and less than or equal to Ra0.35, and the flatness of the bottom surface of the cavity is greater than or equal to 0.1mm and less than or equal to 0.5mm.

According to another aspect of the present invention, a method for reducing the bending of a plastic package is provided, wherein the plastic package is taken out from the plastic package mold and placed in any of the above-mentioned fixtures to complete the cooling process and Be pinched.

Preferably, the plastic package is placed in the fixture at least before its temperature drops to 150 degrees Celsius.

The technical effect of the invention is that the use of the clamp can greatly reduce the bending of the plastic package in the cooling process, and the effect of the clamp on improving the bending of the plastic package is obvious, and the method is simple and efficient.

Description of drawings

The above and other objects and advantages of the present invention will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein the same or similar elements are denoted by the same reference numerals.

Fig. 1 is a schematic perspective structure diagram of a clamp according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of an embodiment of the lower platen structure in Fig. 1, wherein Fig. 2(a) is a top view, and Fig. 2(b) is an A-A sectional view.

FIG. 3 is a schematic diagram of an embodiment of the carrier structure in FIG. 1 .

Fig. 4 is a schematic diagram of an embodiment of the structure of the upper platen in Fig. 1, wherein Fig. 4(a) is a bottom view, and Fig. 4(b) is a front view.

detailed description

The following introduces some of the possible embodiments of the present invention, which are intended to provide a basic understanding of the present invention, but are not intended to identify key or decisive elements of the present invention or limit the scope of protection. It is easy to understand that, according to the technical solution of the present invention, those skilled in the art may propose other alternative implementation manners without changing the essence and spirit of the present invention. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the entirety of the present invention or as a limitation or restriction on the technical solution of the present invention.

In the description, components of various embodiments are described using directional terms (such as "upper," "lower," and "bottom," etc.) and similar terms to indicate directions shown in the drawings or that would be understood by those skilled in the art. Direction of understanding. These directional terms are used for relative description and clarification and are not intended to limit the orientation of any embodiment to a particular direction or orientation.

The inventor of this application found that the bending of the plastic package is largely caused by the cooling process of the plastic package. During the plastic sealing process, the temperature during the injection molding process is relatively high (for example, it can reach about 175 degrees Celsius). The plastic sealing body includes the upper half and the lower half. The lower mold cavity of the plastic sealing mold is formed by plastic film, and the upper mold cavity and the lower mold cavity are combined by a parting surface to form a plastic sealing cavity. Usually, due to the volume difference between the upper mold cavity and the lower mold cavity, the shrinkage of the plastic package on the upper and lower surfaces of the lead frame will be different. Stress will appear inside the plastic package during the cooling process, and the plastic package will bend. Especially for relatively large plastic packages, the bending phenomenon is more obvious.

FIG. 1 is a perspective structure diagram of a clamp according to an embodiment of the present invention. In this embodiment, the jig 10 is used to process the plastic package 910 just taken out of the plastic package mold. The jig 10 includes an upper platen 150 and a lower platen 110 , between which the plastic package 910 is placed for cooling, and to facilitate the transport and transfer of the plastic package 910 , the jig 10 also includes a carrier plate 130 . One or more plastic packages 910 (for example, in the form of a package array) can be placed on the carrier 130 at the same time, and the carrier 130 can also be placed on the upper platen 150 and the lower platen 150 during the process of clamping the plastic package 910 by the clamp 10 Between the pressing plates 110, therefore, the design of the carrier plate 130 needs to design its shape so that it does not affect the action of the upper pressing plate 150 and the lower pressing plate 110 on the plastic sealing body during the crimping process, in addition to satisfying the function of carrying and transferring the plastic package 910. 910 upper and lower surfaces.

FIG. 2 is a schematic diagram of an embodiment of the lower platen structure in FIG. 1 , wherein FIG. 2( a ) is a top view, and FIG. 2( b ) is an A-A cross-sectional view. FIG. 3 is a schematic diagram of an embodiment of the carrier structure in FIG. 1 . Fig. 4 is a schematic diagram of an embodiment of the upper platen structure in Fig. 1, wherein Fig. 4(a) is a bottom view, and Fig. 4(b) is a front view. Each component of the jig 10 will be further described with reference to FIGS. 1 to 4 .

The lower platen 110 is provided with a plurality of cavities 113 on the upper surface of its body 111, and the cavities are used to place the plastic package 910 in a fixed position. Therefore, the shape of the cavity 113 can roughly match the lower mold used for injection molding to form the plastic package. The shape of the cavity is designed so that the plastic package can be roughly embedded in the cavity and positioned. As shown in Figure 2, the cavities 113 can be arranged on the upper surface of the body 111 in rows and columns, and the number and arrangement of the cavities 113 are designed according to the array of the plastic package 910, which is not limited by the present invention. Example limitations. A groove 112 is also provided on the upper surface of the platen body 111 for embedding the carrier plate 130 . Specifically, as shown in FIG. 3 , the carrier 130 is basically formed by a carrier frame 132; during the carrier process, the plastic package or package array is placed on the carrier frame 132; In the groove 112 , so as not to affect the plastic package 910 being clamped by the upper pressing plate 150 and the lower pressing plate 110 . The shape of the groove 112 may specifically be designed corresponding to the shape of the carrying frame 132 . Specifically, the carrier board 130 can also be provided with a handle 131 , which makes it easier to carry and carry the carrier board 130 .

In this embodiment, as shown in FIG. 4 , the lower surface 151 of the upper pressing plate 150 is basically a flat surface. During the crimping process, it directly acts on the upper surface of the plastic package 910 and exerts pressure on the plastic package 910 .

Specifically, immediately after the plastic package 910 is taken out from the plastic sealing mold, it is placed on the carrier plate 130 and positioned on the lower platen 110, and then the upper platen 150 is pressed down, so that the plastic package is cooled in the fixture 10, outside the fixture Under the action of pressure, its forced correction function reduces the thermal stress inside the plastic package due to the cooling process and does not cause the plastic package to be complete, thereby greatly reducing the shape bending of the plastic package 910 .

In a preferred embodiment, a cooling component, such as a circulating water cooling system, is provided in the body of the upper platen 150 or the lower platen 110 , so that the cooling efficiency of the plastic package can be improved, and the plastic sealing efficiency of the package can also be improved.

In another preferred embodiment, in order to minimize the bending of the plastic package, the roughness of the lower surface 151 of the upper pressing plate 150 is set in the range of Ra1 to Ra2 (for example, Ra1.5), and the flatness of the lower surface 151 Set in the range of 0.1mm to 0.5mm (for example, 0.2mm); similarly, the bottom surface of the cavity 113 of the lower pressing plate 110 also acts on the package during the crimping process, therefore, the setting of the cavity 113 of the lower pressing plate 110 The roughness of the bottom surface is in the range of Ra0.1 to Ra0.35 (eg, Ra0.2), and the flatness of the bottom surface of the cavity 113 is set in the range of 0.1 mm to 0.5 mm (eg, 0.2 mm).

The present invention also provides a method for reducing the bending of the plastic package. After the plastic package 910 is injected in the plastic package mold, it is taken out from the plastic package mold, and immediately placed in the clamp 10 of the embodiment shown in FIG. Clamp to avoid warping of the molded body during cooling. Preferably, the plastic package 910 should be placed in the fixture 10 at a temperature greater than or equal to 150 degrees Celsius, that is, the plastic package 910 should be placed in the fixture 10 at least before its temperature drops to 150 degrees Celsius, so that the plastic package The main cooling shrinkage stage of the body is completed in the fixture, which is beneficial to reduce the bending of the plastic package.

The above examples mainly illustrate the jig of the present invention and the method for using the jig to reduce the bending of the plastic package. Although only some of the embodiments of the present invention have been described, those skilled in the art should appreciate that the present invention can be implemented in many other forms without departing from the spirit and scope thereof. The examples and embodiments shown are therefore to be regarded as illustrative and not restrictive, and the invention may cover various modifications without departing from the spirit and scope of the invention as defined in the appended claims with replace.

Claims (6)

1. A fixture for reducing the bending of a plastic package, characterized in that it includes an upper platen and a lower platen, and the plastic package in the cooling process of the plastic package is placed between the upper platen and the lower platen and is held by the The upper pressing plate and the lower pressing plate are clamped; the fixture also includes a carrier plate for simultaneously carrying and transferring a plurality of the plastic packages, and the plastic package and the carrier plate are placed between the upper pressing plate and the lower pressing plate at the same time , the upper surface of the lower pressing plate is provided with a groove, and the carrier plate placed between the upper pressing plate and the lower pressing plate is embedded in the groove, so as not to affect the sealing of the plastic package by the upper pressing plate and the lower pressing plate Clamping. 2 . The clamp according to claim 1 , wherein a cavity for positioning the plastic package is provided on the upper surface of the lower pressing plate. 3 . 3. The jig according to claim 1, wherein the carrying plate comprises a carrying frame and a handle, and the carrying frame is embedded in the groove. 4 . The jig according to claim 1 , wherein a cooling component for accelerating cooling of the plastic package is provided in the upper pressing plate or the lower pressing plate. 4 . 5. The fixture according to claim 1, wherein the roughness of the upper pressing plate acting on the surface of the plastic package is greater than or equal to Ra1 and less than or equal to Ra2, and the roughness of the upper pressing plate acting on the The flatness of the surface of the plastic package is greater than or equal to 0.1 mm and less than or equal to 0.5 mm. 6. The fixture according to claim 2, wherein the roughness of the bottom surface of the cavity is greater than or equal to Ra0.1 and less than or equal to Ra0.35, and the flatness of the bottom surface of the cavity is greater than or equal to 0.1mm and less than or equal to 0.5mm.