JPH11176853A - Semiconductor sealing and forming method, and semiconductor sealing and forming die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide good semiconductor package characteristics by controlling at least one of the filling peak pressure and pressure-holding peak pressure to a particular pressure when performing semiconductor sealed molding for a thermoplastic resin. SOLUTION: In performing semiconductor sealed molding, a semiconductor element such as IC or the like is set and in a cavity 5, thermosetting resin melt from a injection molding machine is injected to dies, and thermoplastic resin is injected and filled from a spool 2 to cavity 5 through a runner 3 and further a gate 4. Injection pressure of the thermoplastic resin in the middle of injection is detected by a pressure sensor 7 which is located at least one of the gate 4 and cavity 5. And the injection molding is performed while controlling the peak pressure of the filling pressure in the middle of injection or the peak pressure after completion of filling to a range of 10 MPa to 60 MPa. Also for the thermoplastic resin, it is desired to have the polyphenylene sulphide as the main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor encapsulation molding method and a semiconductor encapsulation molding die by injection molding of a thermoplastic resin.

[0002]

2. Description of the Related Art A semiconductor package is manufactured by encapsulating a semiconductor element such as an IC with an encapsulating resin. However, when encapsulating and molding a semiconductor element, conventionally, a thermosetting resin such as an epoxy resin is used. It is performed by transfer molding using a material or the like.

On the other hand, in addition to the transfer molding using such a thermosetting resin, it has been reported that semiconductor encapsulation molding is performed by injection molding using a thermoplastic resin such as polyphenylene sulfide or a liquid crystal polymer.

[0004]

However, when semiconductor encapsulation is performed by injection molding, a high pressure acts on the semiconductor element set in the mold during the injection molding to damage the semiconductor element. In addition, there has been a problem that the characteristics of the semiconductor element are deteriorated, and sometimes the semiconductor element may be cracked. In particular, the defect of the semiconductor package is not known immediately after molding, and the defect of molding cannot be determined unless an acceleration test such as PCT is performed. Therefore, the risk of shipping a defective product increases.

The present invention has been made in view of the above points, and has as its object to provide a semiconductor encapsulation molding method and a semiconductor encapsulation molding die capable of obtaining a semiconductor package having good characteristics. It is.

[0006]

According to a first aspect of the present invention, there is provided a semiconductor encapsulation molding method for performing semiconductor encapsulation molding by injection molding of a thermoplastic resin. Is controlled to 10 to 60 MPa. The invention of claim 2 is characterized in that a molding material containing polyphenylene sulfide as a main component is used as the thermoplastic resin.

According to a third aspect of the present invention, a molding material containing a polymer alloy of polyphenylene sulfide and syndiotactic polystyrene as a main component is used as the thermoplastic resin. Claim 4 of the present invention
Is a mold for performing semiconductor encapsulation molding by injection molding of a thermoplastic resin by controlling at least one of the filling peak pressure and the holding pressure to 10 to 60 MPa. It is characterized by comprising a pressure sensor.

According to a fifth aspect of the present invention, there is provided a semiconductor encapsulation mold by controlling at least one of a filling peak pressure and a holding pressure to 10 to 60 MPa and injection molding a thermoplastic resin. Wherein the pressure sensor is provided at the gate.

[0009]

Embodiments of the present invention will be described below. In the present invention, the thermoplastic resin is not particularly limited, but is mainly a molding material containing polyphenylene sulfide (PPS) as a main component, or a polymer alloy of polyphenylene sulfide (PPS) and syndiotactic polystyrene (SPS). A molding material as a component can be used. In the present invention, these thermoplastic resins are particularly effective.

In addition, as a molding machine used for injection molding in the present invention, a commonly used injection molding machine for thermoplastic resin can be used. FIG. 1 shows an example of a mold used for injection molding in the present invention, in which a sprue 2 is formed through a fixed mold 1. The sprue 2 communicates with a plurality of gates 4 via a runner 3 and further communicates with a cavity 5 via each gate 4. The runner 3 and the gate 4 are formed on the movable mold 6 side, and the cavity 5 is formed between the fixed mold 1 and the movable mold 2. In FIG. 1B, reference numerals 8 and 9 denote knockout pins, and the knockout pins 8 and 9 are movable molds 6.
It is provided in.

A pressure sensor 7 is provided on the fixed mold 1 facing the gate 4 immediately after the cavity 5. The pressure sensor 7 may be provided on the fixed mold 1 so as to face the cavity 5. Of course, the pressure sensor 7 may be provided in both the gate 4 and the cavity 5. Gate 4
Even if the pressure is measured by providing the pressure sensor 7 at a position other than the cavity 5 and the cavity 5, no correlation can be found between the measured pressure and the quality of the semiconductor package. As the pressure sensor 7, a commercially available pressure sensor for a plastic molding machine such as a quartz pressure converter can be used. The pressure sensor 7 is connected to a control device having a built-in CPU and the like, so that the injection device can be controlled by the control device according to the pressure detected by the pressure sensor 7.

When performing semiconductor encapsulation molding using the above-described mold, a semiconductor element such as an IC is set in the cavity 5, and a molten thermoplastic resin is injected into the mold from an injection molding machine. A thermoplastic resin is injected from the sprue 2 through the runner 3 and further through the gate 4 into the cavity 5.
And filling. The filling pressure of the thermoplastic resin during injection is detected by a pressure sensor 7 provided in at least one of the gate 4 and the cavity 5. After the injection of the thermoplastic resin into the cavity 5 is completed, the cavity 5 is cooled while maintaining the injection pressure from the injection molding machine in order to maintain the state in which the thermoplastic resin is filled in the cavity 5. Solidifies the thermoplastic resin. At this time, the holding pressure for maintaining the filling state of the thermoplastic resin is applied to the gate 4.
And the pressure sensor 7 provided in at least one of the cavities 5. Then, after the movable mold 6 is moved downward to open the mold, the semiconductor package formed in the cavity 5 is protruded by the knockout pins 8 and 9 and removed to complete the molding.

Here, in the present invention, the peak pressure of the filling pressure during injection and the peak pressure of the holding pressure after the completion of filling are reduced by 10%.
While controlling to be in the range of MPa to 60 MPa,
Injection molding is performed. That is, the filling pressure during injection and the holding pressure after completion of filling are measured by the pressure sensor 7, and the peak pressure of the filling pressure and the peak pressure of the holding pressure are 10M.
When the pressure reaches the upper limit set in the range of Pa to 60 MPa, feedback control is performed so as to lower the injection pressure by the injection molding machine, and the peak pressure of the filling pressure or the holding pressure is set in the range of 10 MPa to 60 MPa. When the pressure reaches the lower limit, the peak pressure of the filling pressure and the peak pressure of the holding pressure are controlled to 10 MPa to 6 by performing feedback control so as to increase the injection pressure by the injection molding machine.
Injection molding is performed while controlling so as not to deviate from the range of 0 MPa.

The management of the peak pressure may be performed for both the peak pressure of the filling pressure and the peak pressure of the holding pressure. However, the management of the peak pressure is performed only for one of the peak pressure of the filling pressure and the peak pressure of the holding pressure. You may. When managing both the peak pressure of the filling pressure and the peak pressure of the holding pressure, the injection molding machine may be controlled based on the higher peak pressure. In this way, by performing injection molding while controlling the peak pressure of the filling pressure during the injection and the peak pressure of the holding pressure after the filling is in the range of 10 MPa to 60 MPa, good characteristics can be obtained. It is possible to form a simple semiconductor package. Peak pressure of filling pressure and peak pressure of holding pressure are 60M
If the pressure exceeds Pa, the semiconductor package formed under such a pressure may be deteriorated in the characteristics of the semiconductor element or cracked in the semiconductor element itself when subjected to heat treatment such as PCT. If the peak pressure of the filling pressure or the peak pressure of the holding pressure is less than 10 MPa, sufficient pressure is not applied to the thermoplastic resin in the cavity 5, and a defective product due to poor filling may be generated.

[0015]

Next, the present invention will be described specifically with reference to examples. As an injection molding machine, "PS40" manufactured by Nissei Plastics Co., Ltd.
/ 5TM "and the mold is TO220F as shown in FIG.
A pressure sensor “TYPE6159A” manufactured by KISTLER was attached to the gate using a package for taking four packages.

As the thermoplastic resin, a molding material prepared with the following composition was used. That is, a linear PPS resin (“W-202A” manufactured by Kureha Chemical Industry Co., Ltd .: 23 Pa · s /
Parallel plate method, 300 ° C, 100 rad / sec
Ionic impurities: sodium 2 ppm, chlorine 1
ppm: electric conductivity 5 μS / cm), 100 parts by weight, graft copolymer of acrylonitrile styrene copolymer onto ethylene / glycidyl methacrylate copolymer (“A4400” manufactured by NOF Corporation: EGMA / AS ratio 70 /
30, GMA 10.5, 330 ° C., weight loss -2.3
%), Milled fiber as inorganic filler ("REV8" manufactured by Nippon Sheet Glass Co., Ltd., aminosilane treatment, fiber diameter 13 m, average fiber length 70 m, arpect ratio 5.
6), 0.7 parts by weight of an aminosilane coupling agent (γ-aminopropyltriethoxysilane, “A1100” manufactured by Nippon Unicar Co., Ltd.) as a coupling agent, and an inorganic ion exchanger (Sb ₂ Bi _1.4 O _6.4) (OH)
_0.9 (NO ₃ ) _0.4 · 0.6 H ₂ O) was uniformly mixed with 1 part by weight using a Henschel mixer, and then a screw diameter of 40
mm using a twin screw extruder with a cylinder temperature of 300 mm.
The mixture was extruded and kneaded under the condition of ° C, and pelletized to prepare a molding material.

Using a Si thyristor element as a semiconductor element, injection molding is performed under the conditions of a mold temperature of 130 ° C. or 180 ° C., a cylinder temperature of 300 ° C., a filling time of 1 second, a dwell time of 5 seconds, and a cooling time of 30 seconds. An evaluation semiconductor package was manufactured. At this time, the peak pressure of the holding pressure after the completion of filling is 200 kg / cm ² (about 20 MPa),
00 kg / cm ² (about 30 MPa), 400 kg / cm
² (about 40MPa), 500kg / cm ² (about 50MP
a), 600 kg / cm ² (about 60 MPa), 700 k
g / cm ² (about 70 MPa), 800 kg / cm ² (about 80 MPa), 900 kg / cm ² (about 90 MPa),
The molding was performed by controlling the injection molding machine while measuring with a pressure sensor so that the pressure became 1000 kg / cm ² (about 100 MPa).

With respect to the semiconductor package thus obtained, 121 ° C./85% RH / 2 atm / 24 hr
The PCT treatment was performed under the conditions described above, and the PCT-treated semiconductor package was boiled for 10 minutes in a mixed solution of fuming sulfuric acid 70% and concentrated sulfuric acid 30% to remove the resin. Was visually observed with a magnifying glass.
The defect occurrence rate is shown in FIG. 2 and FIG. FIG. 2 shows a molding at a mold temperature of 130 ° C., and FIG. 3 shows a molding at a mold temperature of 180 ° C.

As shown in FIGS. 2 and 3, the peak pressure of the holding pressure after the completion of filling is 600 kg / cm ² (about 60M).
In the case of Pa) or less, no defect occurs, but the peak pressure of the holding pressure after completion of filling is 600 kg / cm ² (about 60 M
When it exceeded Pa), a defect occurred. still,
In the case of untreated PCT, no crack is observed even if the peak pressure of the holding pressure after filling is over 600 kg / cm ² (about 60 MPa).

Further, regarding the semiconductor package subjected to the PCT processing as described above, “tektronix” manufactured by Sony Corporation is used.
370A ”, the ON voltage (VON) and the leakage current (I
AKS) and gate leakage current (IKGO). The results are shown in Tables 1 and 2. Table 1 shows the molding at a mold temperature of 180 ° C., and Table 2 shows the molding at a mold temperature of 130 ° C. In addition, the column where no measurement value is entered indicates that a crack has occurred.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

As described above, in the semiconductor encapsulation molding method according to the first aspect of the present invention, when performing semiconductor encapsulation molding by injection molding of a thermoplastic resin, at least one of the filling peak pressure and the holding pressure peak pressure. Is controlled to 10 to 60 MPa, it is possible to perform sealing molding without damaging the semiconductor element, and to obtain a semiconductor package having good characteristics.

The invention of claim 2 is characterized in that a molding material containing polyphenylene sulfide as a main component is used as the thermoplastic resin, and the invention of claim 3 is characterized in that polyphenylene sulfide and syndigo are used as the thermoplastic resin. It is characterized by using a molding material comprising a polymer alloy of tactic polystyrene as a main component, and when using such a thermoplastic resin, particularly good results are obtained by controlling the pressure as described above. Is what you can do.

In a mold for performing semiconductor encapsulation by injection molding of a thermoplastic resin by controlling at least one of the filling peak pressure and the holding pressure to 10 to 60 MPa, The mold is provided with a pressure sensor in the cavity, and the semiconductor encapsulation mold according to claim 5 is provided with a pressure sensor in the gate. ,
Capable of measuring filling peak pressure and holding pressure peak pressure in cavities and gates, accurately measuring filling peak pressure and holding pressure peak pressure, and accurately controlling pressure in the range of 10 to 60 MPa. It is.

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of a semiconductor encapsulation molding die according to the present invention, wherein (a) is a cross-sectional view and (b) is a plan view of a movable die.

FIG. 2 is a graph showing a relationship between a holding pressure peak pressure in a cavity at a mold temperature of 130 ° C. and a defective rate.

FIG. 3 is a graph showing a relationship between a holding pressure peak pressure in a cavity at a mold temperature of 180 ° C. and a defective rate.

[Explanation of symbols]

 4 Gate 5 Cavity 7 Pressure sensor

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29C 45/77 B29C 45/77 H01L 23/29 H01L 23/30 R 23/31 // B29K 25:00 81:00 B29L 31:34

Claims (5)

[Claims] 1. A semiconductor encapsulation molding method, wherein at least one of a filling peak pressure and a holding pressure peak pressure is controlled to 10 to 60 MPa when performing semiconductor encapsulation molding by injection molding of a thermoplastic resin. 2. The method according to claim 1, wherein a molding material containing polyphenylene sulfide as a main component is used as the thermoplastic resin. 3. The method according to claim 1, wherein a molding material mainly containing a polymer alloy of polyphenylene sulfide and syndiotactic polystyrene is used as the thermoplastic resin. 4. A mold for performing semiconductor sealing molding by injection molding of a thermoplastic resin by controlling at least one of a filling peak pressure and a holding pressure to 10 to 60 MPa, wherein a pressure sensor is provided in a cavity. A semiconductor encapsulation molding die comprising: 5. A mold for performing semiconductor encapsulation molding by injection molding of a thermoplastic resin by controlling at least one of a filling peak pressure and a holding pressure to 10 to 60 MPa, wherein a pressure sensor is provided at a gate. A semiconductor encapsulation molding die comprising: