JP2801899B2 - Mold for forming protective body of semiconductor chip package - Google Patents

Abstract

The apparatus manufactures a protective encapsulation for semiconductor chip (10) and includes upper and lower mould halves (100,102). Moulding tools form, when closed a mould space from injection of moulding compound and receive the semiconductor chip arranged on the chip frame. Upper and lower plate arrangement (80) open and close the moulding tools. The plate arrangement has with two ejection pins (4,9,8) for ejecting the mould part (104) forming the protection encapsulation immediately following its formation. A central ejection pin (13) is provided on the lower plate arrangement (80b) and likewise extends into the moulding space (6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for forming a protective body of a semiconductor chip package, and more particularly, to a plastic package body for protecting a semiconductor chip mounted on a lead frame. A mold used in a transfer molding process for forming a semiconductor chip, the semiconductor chip including an intermediate extrusion pin for reducing a molding stress applied to the semiconductor chip and preventing cracks of the chip and the package body. The present invention relates to a mold for forming a protective body of a package.

[0002]

2. Description of the Related Art The purpose of a semiconductor chip package is to form a protective body for ensuring the normal operation and reliability of an integrated circuit device, and to electrically connect the integrated circuit device to an external system. It is to provide a means. In the case where the semiconductor chip package is formed with a protective package body by a plastic molding process using a thermosetting resin or a thermoplastic resin, the reliability is inferior to the ceramic package, but the manufacturing cost can be reduced. There is an advantage that mass production is possible.

[0003] Transfer molding processes are most widely used to form plastic package bodies. In this step, after mounting the lead frame strip with the semiconductor chip attached to the mold, the high-temperature liquid molding compound contained in the predetermined container is injected into the mold cavity, and finally the packaged product Is the process of extruding. The mold is composed of an upper mold and a lower mold. The upper and lower molds are opened when a lead frame having a semiconductor chip attached thereto is mounted and extruded, and a molding compound is formed. Will be closed when injecting into the cavity.
The design of the mold greatly affects the yield of the assembly process and the reliability of the packaged product.

FIG. 3A is a cross-sectional view showing a state in which the conventional upper and lower molds are opened and the semiconductor chip-lead frame assembly is mounted. FIG. 3B is a sectional view showing the upper and lower molds. Is a sectional view showing a state in which the molding compound is injected and the molding compound is injected, and FIG. 4 is a sectional view showing a state in which the package body is extruded from the mold after the completion of molding.

[0005] The upper mold 100 and the lower mold 102 have a pair of mold plates 90a, 90b and mounting plates 80a, 80b, respectively.
It is composed of The mounting plates 80a and 80b are large iron blocks, and are fixed to upper and lower molding presses (not shown) by bolts or the like. The lower mounting plate 80b is composed of a drive mounting plate 1b and an extrusion pin mounting plate 2b.
b. The two lower push pins 8 serve to push up the molded part from the cavity 6. The drive mounting plate 1b is heated by a heater (not shown) so that the mold plate 90 maintains a constant mold temperature. Like the lower mounting plate 80b, the upper mounting plate 80a includes a drive mounting plate 1a and an extrusion pin mounting plate 2a. The identification pin 4 and the upper extrusion pin 9 are coupled to the extrusion pin mounting plate 2a. ing. Such a mounting plate must be designed to be able to withstand the pressure of the molding press up to several tons.

The mold plates 90a and 90b are parts that directly contact the molding compound during the molding process and determine the shape of the package body. The templates 90a, 90b each include a housing 3a, 3b and a cavity bar 5a, 5b. The hot liquid molding compound is applied to the molding path and the cavity bars 5a, 5a
b, is injected into the cavity 6 through a gate (not shown), and the air that has entered the cavity at this time is passed through an air outlet (not shown) provided in the cavity bar. Get out.

[0007] As shown in FIG.
0 and the semiconductor chip 10 with the lower mold 102 opened.
Are aligned with the cavity 6. The semiconductor chip 10 is electrically connected to a lead frame by bonding wires 11.

As shown in FIG. 3B, the upper and lower molds 100 and 102 are closed, and the molding compound 104 is injected into the cavity 6 through the gate and the molding path. The molding compound 104 has an adhesive property in order to improve the bonding force between the semiconductor chip 10 and the lead frame 7. Therefore, the molding compound 104 is formed on the surfaces of the upper and lower cavity bars 5 a and 5 b forming the cavity 6. Also adhered to. Therefore,
As shown in FIG. 4, in order to remove the molded product from the mold, a separate identification pin 4 and an extrusion pin 8,
9 must be used.

The extrusion process of removing the molded product from the mold is as follows.

First, after injection of the molding compound,
At the same time as the upper mounting plate 80a and the upper template 90a are raised, the identification pin 4 and the upper push-out pin 9 are moved to the
Push out 04. Next, when the lower mold plate 90b is lowered while the lower mounting plate 80b is fixed, the package body 104 is separated from the contact surface of the lower cavity bar 5b by the lower push pins 8.

The positions of the identification pin 4 and the upper push pin 9 projecting from the upper cavity bar 5a are shown in FIG. 5A, and the lower push pin 8 projecting from the lower cavity 5b.
Is shown in FIG. 5 (B).

[0012]

However, when the molding process is performed by using such a conventional die having an extrusion pin structure, the following problems occur.

As described above, since the molding compound has adhesiveness, the molding compound also adheres to the surfaces of the upper and lower molds forming the cavity. Of course, after molding, to facilitate extrusion, the surface of the mold forming the cavity can be electroplated with chromium or surface treated with titanium nitride, but the reliability of the molding compound is high. As the strength is improved, the adhesive strength of the molding compound is improved, so that the adhesive strength between the mold surface and the molding compound is still present.

On the other hand, the molded package body is not in a completely solid state but in a soft state. Therefore, the extruded product is put into an oven or the like and completely cured. Therefore, when the package body in a soft state is pushed up by using the lower push-out pins 8, the package body is bent, causing cracks in the semiconductor chips and cracks in the package body. It has been observed that such cracks mainly occur in the short direction at the center of the chip or package body. In addition, there is a possibility that the package body may be separated from the lead frame due to the bending of the package body.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a mold for forming a protective body of a semiconductor chip package which can prevent cracks occurring in the semiconductor chip and the package body.

Another object of the present invention is to provide a mold for forming a protective body of a semiconductor chip package which prevents the package body from peeling off from a lead frame-semiconductor chip assembly.

[0017]

According to a first aspect of the present invention, there is provided a mold for forming a protective body of a semiconductor chip package, comprising a pair of an upper mold and a lower mold. A mold, wherein each of the upper mold and the lower mold is filled with a high-temperature liquid molding compound and has a pair of upper and lower molds having a cavity forming a desired package body; and And a pair of upper and lower mounting plates for opening and closing the lower template, and fixed to the upper mounting plate, protruding to the cavity, and after completing injection of the molding compound into the cavity, the package body is removed. An identification pin to be pushed out and an upper push-out pin, fixed to the lower mounting plate,
A first lower extrusion pin and a second lower extrusion pin for projecting the molding body into the cavity and extruding the package body after completing the injection of the molding compound into the cavity; the first lower extrusion pin and the second lower extrusion pin; The gist is that a lower intermediate extrusion pin is located between the pins, and the lower intermediate extrusion pin is fixed to the lower mounting plate and protrudes to the cavity. Therefore, cracks generated in the semiconductor chip and the package body can be prevented. Further, it is possible to prevent the package body from peeling off from the lead frame-semiconductor chip assembly.

According to a second aspect of the present invention, an upper intermediate push pin is located between the identification pin and the upper push pin.
The gist of the present invention is that the upper intermediate push pin is fixed to the upper mounting plate and protrudes to the cavity. Therefore, the bending of the package body is reduced, and the stress intensity applied to the semiconductor chip is also reduced.

A third invention according to claim 3 is the first invention,
The second lower extrusion pin and the lower intermediate extrusion pin are arranged in a straight line. Therefore, the bending of the package body is reduced, and the stress intensity applied to the semiconductor chip is also reduced.

According to a fourth aspect of the present invention, the identification pin, the upper push pin and the upper intermediate push pin are arranged in a straight line. Therefore, the bending of the package body is reduced, and the stress intensity applied to the semiconductor chip is also reduced.

According to a fifth aspect of the present invention, the first,
The second lower push pin and the lower intermediate push pin are arranged in parallel with the longitudinal edge of the lower mounting plate. Therefore, the bending of the package body is reduced, and the stress intensity applied to the semiconductor chip is also reduced.

According to a sixth aspect of the present invention, in the first aspect,
The second lower push pin and the lower middle push pin are arranged in a diagonal direction with respect to a longitudinal edge of the lower mounting plate. Therefore, the bending of the package body is reduced, and the stress intensity applied to the semiconductor chip is also reduced.

According to a seventh aspect of the present invention, the identification pin, the upper push pin and the upper intermediate push pin are arranged in a diagonal direction with respect to a longitudinal edge of the upper mounting plate. Make a summary. Therefore, the bending of the package body is reduced, and the stress intensity applied to the semiconductor chip is also reduced.

According to an eighth aspect of the present invention, the identification pin, the upper push pin, and the upper intermediate push pin are arranged in parallel with a longitudinal edge of the upper mounting plate. Therefore, the bending of the package body is reduced, and the stress intensity applied to the semiconductor chip is also reduced.

In a ninth aspect of the present invention, the molding compound is a plastic resin. Therefore, the molding compound adheres to the surfaces of the upper and lower molds forming the cavity.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a mold according to the present invention, FIG. 2 (A) is a view showing an arrangement of extrusion pins of a lower mold according to the present invention, and FIG. 2 (B) is a view of the present invention. FIG. 4 is a diagram illustrating an arrangement of extrusion pins of a lower mold according to an embodiment.

The structures of the mold plates 90a and 90b and the mounting plates 80a and 80b, excluding the extrusion pins, are the same as those of the mold of FIG.

An identification pin 4 is provided on the upper cavity bar 5a.
In addition, not only the upper push pin 9 but also the upper middle push pin 12 protrudes. Also, the lower cavity bar 5b has
A lower intermediate extrusion pin 13 protrudes between the two lower extrusion pins 8. 2 (A) and 2 (B) show the arrangement of the identification pins 4, the upper push pins 9 and the upper middle push pins 12 with reference to the upper cavity bar 5a or the lower cavity bar 5b. FIGS. 2A and 2B also show the case where the arrangement is shown with reference to the longitudinal edge of the upper mounting plate 80a described in claims 5 and 6 of the range.
Has the same arrangement relationship as.

The molding compound is placed in the cavity 6
After the package body is extruded, an upper intermediate extrusion pin 12 and a lower intermediate extrusion pin 13
Extrudes the central portion of the package body, thereby reducing the bending of the package body and reducing the stress intensity applied to the semiconductor chip.

FIG. 2C is a view showing the arrangement of the extrusion pins of the lower mold according to another embodiment of the present invention.
(D) is a diagram showing the arrangement of the extrusion pins of the lower mold according to still another embodiment of the present invention.

The arrangement of the push-out pins can take various forms, provided that the intermediate push-out pins 12, 13 are each located intermediate between the identification pin and the upper push-out pin and between the two lower push-out pins. Is preferred. In addition, FIG.
In (D), the arrangement of the lower extrusion pin 8, the lower intermediate extrusion pin 13, and the lower extrusion pin 8 is shown with reference to the upper cavity bar 5a or the lower cavity bar 5b. Lower mounting plate 80 described in
When the arrangement is shown with reference to the edge portion in the longitudinal direction of b, the arrangement relationship is the same as in FIGS. 2C and 2D.

[0033]

Embodiments of the present invention will be specifically described below with reference to Tables 1 and 2 and Equation 1 below.

First, in the extrusion process after molding, the degree of bending of the package body is proportional to the bonding force between the molding compound and the surface of the mold. This is because the force for pushing up the package body is further increased.

The following Table 1 shows the results of experiments conducted by the present inventors to examine the bonding force between the molding compound and the mold surface according to the type of the molding compound and the number of times of molding.

[0036]

[Table 1] In Table 1 above, the unit of the bonding force between the molding compound and the mold surface is Kg / cm ² . Molding compound type A and type B are both bisphenol epoxy molding compounds, and type B is an improved filler in order to make the viscosity higher than type A. Measurement of bonding force is done by push-pull gauge
(Push-pull gauge). As is clear from Table 1, as the number of times of molding increases, the bonding force increases, and the bending phenomenon of the package body also increases.

On the other hand, in order to guarantee the prevention of cracks in the semiconductor chip and the package, it is preferable that the bonding force be 5 kg / cm ² or less.

Table 2 below shows the relationship between the package crack and the chip crack depending on the load applied to the chip and the degree of bending of the package body during extrusion.

[0039]

[Table 2] The size of the semiconductor chip used in this experiment was 24
3.5 μm × 592 μm, and the thickness of the chip is 30 μm.
0 μm, package form is 24 TSOPLOC30
It is 0mil. This experiment is a value obtained by applying a load increasing by 0.5 g to six package elements. For example, when a 2.0 kg load was applied to six package elements, a semiconductor chip crack was found in one element.

As can be seen from Table 2, the load and the degree of bending that cause the semiconductor chip crack are 2 kg and 0.07 mm, respectively, while the load and the degree of bending that cause the package body crack are 3.5 kg and 0.5 kg, respectively. 13 mm is the minimum value. Such experimental data can be theoretically explained by the following equation.

[0041]

(Equation 1) Here, t is the thickness of the semiconductor chip, w is the width, l is the length, P is the load applied in the thickness direction of the chip, a is the scratch depth, and K is Stress intensity. Scratch occurs in a wafer backside polishing process in which the backside of a wafer is polished with a grinder to reduce the thickness of the wafer. The V-groove-shaped scratch is so fine that it cannot be discerned by the naked eye, but the load applied to the chip is concentrated on this portion, causing a chip crack.

If a / t≪1, then K = P (l / w) √a / t ² . Here, the growth rate of the chip crack is proportional to K squared n. Here, n differs depending on the physical characteristics of the sample to which the load P is applied. In the case of a silicon semiconductor chip, n usually has a value of 1 to 2. Therefore,
Stress intensity K closely related to chip crack
Is proportional to the square root of the load, the length of the tip and the screech depth a, but inversely proportional to the width and thickness of the tip.

As described above, cracks in a semiconductor chip can be reduced by changing the components of the molding compound to reduce the bonding force between the molding compound and the mold surface, or by reducing the stress intensity exerted on the semiconductor chip. Can be prevented. In order to reduce the bonding force, it is possible to improve the molding compound or the surface treatment method of the mold for forming the cavity. However, the present invention focuses on reducing the stress strength by deforming the mold structure, thereby preventing semiconductor chip cracks and package cracks.

[0044]

As described above, the mold for forming the protective body of the semiconductor chip package according to the first invention has a cavity in which a high-temperature liquid molding compound is injected and a desired package body is formed. A first lower extrusion pin and a second lower extrusion pin that are fixed to a lower mounting plate that opens and closes a lower mold plate, that protrudes to the cavity, and that extrudes a package body after completing injection of a molding compound into the cavity. A lower intermediate extrusion pin is located between the lower intermediate extrusion pins, and the lower intermediate extrusion pins are fixed to the lower mounting plate and are protruded to the cavities. , Cracks in the chip and the package body can be prevented.

According to a second aspect of the present invention, an upper intermediate push pin is located between the identification pin and the upper push pin, and the upper intermediate push pin is fixed to the upper mounting plate and protrudes to the cavity. The bending of the package body is reduced, and the stress intensity applied to the semiconductor chip is also reduced.

According to a third aspect of the present invention, since the first and second lower push pins and the lower intermediate push pin are arranged in a straight line, the bending of the package body is reduced, and the stress intensity applied to the semiconductor chip is also reduced. Decrease.

According to a fourth aspect of the present invention, since the identification pins, the upper push pins and the upper intermediate push pins are arranged in a straight line, the bending of the package body is reduced, and the strength of the stress applied to the semiconductor chip is also reduced. .

According to a fifth aspect of the present invention, since the first and second lower push pins and the lower intermediate push pin are arranged in parallel with the longitudinal edges of the lower mounting plate, the bending of the package body is reduced. In addition, the stress applied to the semiconductor chip is also reduced.

According to a sixth aspect of the present invention, the first and second lower push pins and the lower intermediate push pin are arranged in a diagonal direction with respect to a longitudinal edge of the lower mounting plate. The bending is reduced and the stress intensity applied to the semiconductor chip is also reduced.

According to a seventh aspect of the present invention, the identification pin, the upper push pin and the upper intermediate push pin are arranged diagonally with respect to the longitudinal edge of the upper mounting plate, so that the package body can be bent. And the stress intensity applied to the semiconductor chip is also reduced.

According to an eighth aspect of the present invention, since the identification pins, the upper push pins and the upper intermediate push pins are arranged in parallel with the longitudinal edges of the upper mounting plate, the bending of the package body is reduced, and The stress intensity applied to the chip is also reduced.

According to the ninth aspect of the present invention, since the molding compound is a plastic resin, the molding compound adheres to the surfaces of the upper and lower molds forming the cavity.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold according to the present invention.

FIG. 2A is a view showing the arrangement of extrusion pins of an upper mold according to the present invention, and FIG. 2B is a view showing the arrangement of extrusion pins of a lower mold according to an embodiment of the present invention; (C) is a diagram showing an arrangement of extrusion pins of a lower mold according to another embodiment of the present invention, and (D) is a diagram showing an arrangement of extrusion pins of a lower mold according to still another embodiment of the present invention. It is.

FIG. 3A is a cross-sectional view showing a state in which a conventional upper and lower mold is opened and a semiconductor chip-lead frame assembly is mounted, and FIG. 3B is a sectional view in which the upper and lower molds are closed; It is sectional drawing which shows the state in which a molding compound is inject | poured into a cavity.

FIG. 4 is a sectional view showing a state in which a molded package body is extruded from a mold.

FIG. 5A is a diagram showing a position of an extrusion pin of a conventional upper mold, and FIG. 5B is a diagram showing a position of an extrusion pin of a conventional lower mold.

[Explanation of symbols]

 1a, 1b Drive mounting plate 2a, 2b Extrusion pin mounting plate 3a, 3b Housing 4 Identification pin 5a, 5b Cavity bar 7 Lead frame 8 Lower extrusion pin 9 Upper extrusion pin 10 Semiconductor chip 11 Bonding wire 12 Upper middle extrusion pin 13 Lower middle Extrusion pin 80a, 80b Mounting plate 90a, 90b Mold plate 100 Upper mold 102 Lower mold 104 Package body

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kim Yong-Hong 74 74 Kita-Suriyama, Haifang-myeon, Asan-si, Chungcheongnam-do, Republic of Korea (56) References JP-A-60-257528 (JP, A) JP-A-5 −74827 (JP, A) Japanese Utility Model Showa 57-14437 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/56

Claims (9)

(57) [Claims] An upper mold and a lower mold are provided in a pair. Each of the upper mold and the lower mold has a cavity in which a high-temperature liquid molding compound is injected and a desired package body is formed. A pair of upper and lower templates, a pair of upper and lower mounting plates for opening and closing the upper and lower templates, fixed to the upper mounting plate, projecting up to the cavity, and the cavity After the injection of the molding compound is completed, the identification pin and the upper extrusion pin for extruding the package body are fixed to the lower mounting plate, protruded to the cavity, and the injection of the molding compound into the cavity is completed. And a first lower push pin and a second lower push pin for pushing the package body, wherein the first lower push pin and the second lower push pin are provided. A lower intermediate push pin is located between the pins, and the lower intermediate push pin is fixed to the lower mounting plate and protrudes to the cavity to form a protective body of the semiconductor chip package. Molds for. 2. An upper intermediate push pin is located between the identification pin and the upper push pin, and the upper intermediate push pin is fixed to the upper mounting plate and protrudes to the cavity. Item 7. A mold for forming a protective body of a semiconductor chip package according to Item 1. 3. The metal for forming a protective body of a semiconductor chip package according to claim 1, wherein the first and second lower push pins and the lower middle push pin are arranged in a straight line. Type. 4. The mold for forming a protective body of a semiconductor chip package according to claim 2, wherein the identification pin, the upper push pin and the upper intermediate push pin are arranged in a straight line. 5. The semiconductor chip package according to claim 3, wherein the first and second lower push pins and the lower intermediate push pin are arranged in parallel with a longitudinal edge of the lower mounting plate. Mold for forming the protective fuselage. 6. The apparatus according to claim 3, wherein the first and second lower push pins and the lower intermediate push pin are arranged diagonally with respect to a longitudinal edge of the lower mounting plate. For forming the protective body of the semiconductor chip package of FIG. 7. The semiconductor according to claim 4, wherein the identification pin, the upper push pin, and the upper middle push pin are arranged diagonally with respect to a longitudinal edge of the upper mounting plate. A mold for forming the protective body of the chip package. 8. The protection of a semiconductor chip package according to claim 4, wherein the identification pin, the upper push pin, and the upper middle push pin are arranged in parallel with a longitudinal edge of the upper mounting plate. A mold for forming the fuselage. 9. The mold for forming a protective body of a semiconductor chip package according to claim 1, wherein the molding compound is a plastic resin.