JPH0645384A - Mold for sealing semiconductor and using mehtod therefor - Google Patents

Abstract

PURPOSE:To prevent deformation such as a positional deviation, inclination, etc., of a semiconductor element during resin filling by providing semiconductor element fixing means in a mold to be used to seal a resin-sealed semiconductor device. CONSTITUTION:A packing 6 and a cavity 7 inside the packing 6 are provided at parts of a semiconductor sealing mold in contact with a lower surface of a semiconductor element 3 on a lower mold 1, and an exhaust tube 8 for reducing under pressure the cavity 7 is provided. The cavity 7 is reduced in pressure thereby to bring the element 3 into close contact with the packing 6 thereby to prevent filling of resin to the lower surface of the element 3 and deformation by fixing the element 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for semiconductor encapsulation and a method of using the same.

[0002]

2. Description of the Related Art A conventional molding die for semiconductor encapsulation has an upper die 2 and a lower die 1 as shown in FIG.
A cavity 9 is provided between the upper mold 2 and the lower mold 1. This molding die shows a state in which the semiconductor element 3 and the lead 4 of the semiconductor device, which is an enclosed object, are sandwiched between the upper die 2 and the lower die 1 via the tape material 5.

Thereafter, although not shown, a sealing resin is injected from a pot portion separately provided in the mold, and the sealing resin is filled into the cavity 9 through the runner and the gate. Further, thereafter, after the filling is completed and a predetermined curing time of the sealing resin has elapsed, the space between the upper mold 2 and the lower mold 1 is opened, and the semiconductor device including the semiconductor element 3 and the lead 4 that have been resin-molded are completed. Is taken out to complete a series of sealing steps.

As an improvement of this method, as shown in the sectional view of FIG. 5, a method of bringing the lower surface of the semiconductor element 3 into contact with the lower mold 1 and filling the resin is also used. In this method, the thickness of the semiconductor device after sealing becomes thin, and no resin exists in the portion where the lower surface of the semiconductor element 3 is in contact with the lower mold 1. Therefore, the deformation of the semiconductor element 3 is reduced. However, the resin may infiltrate between the semiconductor element 3 and the lower mold 1, and the semiconductor element 3 may be deformed.

[0005]

In this conventional molding die, as shown in FIG. 4, when the cavity 9 is filled with the sealing resin, the viscosity thereof drags the semiconductor element 3 and the lead 4 inside the cavity 9 or In some cases, it moved to a position that deviated from its original position in order to push it. When the deformation is not returned to the original state and the filling is completed and the sealing resin is cured, the deformation and positional displacement of the semiconductor element 3 and the lead 4 become decisive, resulting in defective molding.

Even when the resin is filled by the method shown in FIG. 5, the resin may be filled between the semiconductor element 3 and the lower mold 1, causing deformation and displacement. It is also known that such deformation and positional displacement lead to disconnection between the semiconductor element 3 and the lead 4 in the worst case. These problems have become remarkable as semiconductor devices have become thinner in recent years, and countermeasures against them have been desired.

[0007]

According to the molding die and method of using the same of the present invention, it is possible to solve the problems such as the deformation and displacement of the semiconductor element and the lead and to provide a highly reliable thin semiconductor device. In order to fix the semiconductor element by adhering the lower surface of the semiconductor element to the lower mold, it is possible to prevent the lower surface of the semiconductor element from being filled with resin. The function is to fix the semiconductor element by adhering the lower surface of the semiconductor element to the airtight part (packing) provided in the lower mold, eliminating the resin filling of the lower surface of the semiconductor element, and reducing the stress due to the viscosity of the resin. This eliminates deformation and misalignment of the semiconductor element and leads.

[0008]

The present invention will be described below with reference to the drawings. 1 is a sectional view of a molding die according to a first embodiment of the present invention. A packing 6 is provided in a portion of the lower mold 1 that is in contact with the lower surface of the semiconductor element 3, and a cavity 7 and an exhaust pipe 8 are provided inside the packing 6, which is the same as the conventional mold.

In the resin encapsulation process, the semiconductor device is placed in the lower mold 1 and then sandwiched between the upper mold 2 and the lower mold 1 to form the cavity 9. At this time, the cavity 7 is depressurized from the exhaust pipe 8 by using a vacuum pump or the like to bring the lower surface of the semiconductor element 3 and the packing 6 into close contact with each other. The packing 6 has a slightly larger outer shape than the semiconductor element 3 and is made of a heat resistant material. Sealing is performed in this state, and when the upper mold 2 and the lower mold 1 are opened, the cavity 7 is returned to normal pressure, and the semiconductor device is taken out. In the first embodiment, the semiconductor device 3
Since the cavity 7 is decompressed, the cavity 7 is closely attached and fixed to the packing 6, and since the lower surface of the semiconductor element 3 is not filled with resin, the deformation of the semiconductor element 3 due to the viscosity of the sealing resin can be prevented. .

FIG. 2 is a sectional view of a molding die according to the second embodiment of the present invention. A plate-shaped packing 6 having a slightly larger outer shape than the semiconductor element 3 is provided on a portion of the lower die 1 which is in contact with the lower surface of the semiconductor element 3, and the packing 6 has a groove 7a on its surface and reduces the pressure of the groove 7a. The lower die 1 is provided with an exhaust pipe 8 for lowering the temperature, and a cavity 9 is not provided below the lead 4 of the lower mold 1. Other than this, it is the same as the conventional molding method.

In the second embodiment, the plate-like packing 6 has a groove 10 as shown in the plan view of FIG. 3 and an exhaust pipe 8 for reducing the pressure of the groove 10. Therefore, the semiconductor element 3
Even when is large, it is possible to prevent distortion at the time of contact with the semiconductor element 3. Further, since the cavity 9 does not exist in the lower surface portion of the tape material 5, the resin only fills the cavity 9 on the upper surface of the lead 4, and the deformation of the lead 4 can be prevented. The material of the packing 6 is heat resistant and silicon rubber or the like can be used.

The following table shows the results of comparative evaluation of the conventional example and the example. The average value of n = 100, the thickness of the semiconductor device,
Deformation (tilt, vertical displacement) of the semiconductor element is shown.

[0013]

[Table 1]

[0014]

As described above, the present invention eliminates the resin filling on the lower surface of the semiconductor element, and has the effect of reducing the deformation of the semiconductor element after sealing.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the present invention.

FIG. 3 is a top view of the packing in FIG.

FIG. 4 is a cross-sectional view of a conventional mold.

FIG. 5 is a cross-sectional view of another conventional mold.

[Explanation of symbols]

 1 Lower Mold 2 Upper Mold 3 Semiconductor Element 4 Lead 5 Tape Material 6 Packing 7 Cavity 7a Groove 8 Exhaust Pipe 9 Cavity 10 Groove

Claims (2)

[Claims] 1. In a molding die for semiconductor encapsulation for resin-sealing a semiconductor device, a packing is interposed in at least a part of a portion of the lower mold which comes into contact with the lower surface of the semiconductor element, and a cavity is provided inside the packing. A molding die for semiconductor encapsulation, wherein the lower die is provided with an exhaust pipe for decompressing the hollow portion. 2. A method of using a molding die for semiconductor encapsulation for resin-sealing a semiconductor device, wherein the lower surface of a semiconductor element is brought into contact with the packing, and the semiconductor device is sandwiched by upper and lower dies,
A method of using a molding die for semiconductor encapsulation, comprising depressurizing the cavity to bring a semiconductor element into close contact with a packing, and injecting a resin into the die to seal the resin except the lower surface of the semiconductor element.